clarified globals; protect other bufs from ve=onemore; misc improvements

README.markdown

@@ -14,13 +14,15 @@ The _pencil_ plugin aspires to make Vim as powerful a tool for writers as
 it is for coders by focusing narrowly on the handful of tweaks needed to
 smooth the path to writing prose.
 
-* For editing files in _text_, _markdown_, _textile_, and other prose-oriented file types
+* For editing files in _text_, _markdown_, _textile_, and other
+  prose-oriented file types
 * Agnostic on soft line wrap _versus_ hard line breaks, supporting both
 * Auto-detects wrap mode via modeline and sampling
 * Adjusts navigation key mappings to suit the wrap mode
 * Creates undo points on common punctuation
 * When using hard line breaks, enables autoformat while inserting text
-* Buffer-scoped configuration (leaves your global settings alone)
+* Buffer-scoped configuration (with a few minor exceptions, _pencil_
+  preserves your global settings)
 * Pure Vimscript with no dependencies
 
 Need spell-check and other features? Vim is about customization. To
@@ -29,15 +31,15 @@ its rich ecosystem of plugins.
 
 ## Why use Vim for writing?
 
-With plenty of word processing apps available, including those that
-specifically cater to writers, why use a programmer’s editor like Vim for
-writing? 
+With plenty of word processing applications available, including those
+that specifically cater to writers, why use a programmer’s editor like Vim
+for writing?
 
 There are good reasons NOT to use Vim for writing:
 
 * Primitive in certain respects (no WYSIWYG or proportionally spaced
   characters, e.g.)
-* A modal editor with a steep learning curve
+* A modal editor with a relatively steep learning curve
 * Time and effort to configure to your needs
 
 But Vim offers a unique editing environment not matched by other writing
@@ -54,9 +56,9 @@ tools:
 Install using Pathogen, Vundle, Neobundle, or your favorite Vim package
 manager.
 
-_For those new to Vim: before installing this plugin, you should first
-work through one of the many tutorials available to get comfortable with
-the basics of Vim._
+_For those new to Vim: before installing this plugin, consider getting
+comfortable with the basics of Vim by working through one of the many
+tutorials available._
 
 ## Configuration
 
@@ -161,7 +163,7 @@ reformat paragraphs with standard Vim commands:
 * `ggVGgq` or `:g/^/norm gqq` - format all paragraphs in buffer
 * `:%norm vipJ` - unformat all paragraphs in buffer
 
-Optionally, you can map these sequences to underutilized keys in your
+Optionally, you can map these operations to underutilized keys in your
 `.vimrc`:
 
 ```vim
@@ -221,8 +223,8 @@ At the bottom of this document is a odd-looking code:
 <!-- vim: set tw=74 :-->
 ```
 
-This is an optional ‘modeline’ that tells Vim to run the following command 
-upon loading the file into a buffer:
+This is an **optional** ‘modeline’ that tells Vim to run the following
+command upon loading the file into a buffer:
 
 ```vim
 :set textwidth=74

autoload/pencil.vim

@@ -78,7 +78,7 @@ function! pencil#init(...) abort
   let l:wrap_arg = get(l:args, 'wrap', 'detect')
 
   if (b:wrap_mode && l:wrap_arg ==# 'toggle') ||
-   \ l:wrap_arg =~# '^\(off\|disable\|false\)$'
+   \ l:wrap_arg =~# '^\(0\|off\|disable\|false\)$'
     let b:wrap_mode = s:WRAP_MODE_OFF
   elseif l:wrap_arg ==# 'hard'
     let b:wrap_mode = s:WRAP_MODE_HARD
@@ -93,7 +93,7 @@ function! pencil#init(...) abort
 
   " translate default(-1) to soft(1) or hard(2) or off(0)
   if b:wrap_mode == s:WRAP_MODE_DEFAULT
-    if g:pencil#wrapModeDefault =~# '^\(off\|disable\|false\)$'
+    if g:pencil#wrapModeDefault =~# '^\(0\|off\|disable\|false\)$'
       let b:wrap_mode = s:WRAP_MODE_OFF
     elseif g:pencil#wrapModeDefault ==# 'soft'
       let b:wrap_mode = s:WRAP_MODE_SOFT
@@ -130,45 +130,48 @@ function! pencil#init(...) abort
     setlocal colorcolumn<
   endif
 
+  " global settings
   if b:wrap_mode
-    setlocal autoindent         " needed by fo=n
-    setlocal nolist
-    setlocal wrapmargin=0
-    setlocal display+=lastline
-    setlocal formatoptions+=1   " don't break line before 1 letter word
-    setlocal formatoptions+=t
-    setlocal formatoptions+=n   " recognize numbered lists
-
-    if g:pencil#cursorwrap
-      setlocal whichwrap+=<,>,h,l,[,]
-      setlocal virtualedit+=onemore        " could break other plugins
+    set display+=lastline
+    set backspace=indent,eol,start      " via tpope/vim-sensible
+    if g:pencil#joinspaces
+      set joinspaces         " two spaces after .!?
+    else
+      set nojoinspaces       " only one space after a .!? (default)
+    endif
   endif
 
-    " clean out stuff we likely don't want
-    setlocal formatoptions-=2
-    setlocal formatoptions-=v
+  " because ve=onemore is relatively rare and could break
+  " other plugins, restrict its presence to buffer
+  " Better: restore ve to original setting
+  if b:wrap_mode && g:pencil#cursorwrap
+    set whichwrap+=<,>,h,l,[,]
+    augroup pencil_cursorwrap
+      autocmd BufEnter <buffer> set virtualedit+=onemore
+      autocmd BufLeave <buffer> set virtualedit-=onemore
+    augroup END
+  else
+    silent! autocmd! pencil_cursorwrap * <buffer>
+  endif
 
-    " trailing whitespace continues paragraph
-    " makes autoformat behave oddly where spaces aren't present
-    setlocal formatoptions-=w
+  " window/buffer settings
+  if b:wrap_mode
+    setlocal nolist
+    setlocal wrapmargin=0
+    setlocal autoindent         " needed by formatoptions=n
+    setlocal formatoptions+=n   " recognize numbered lists
+    setlocal formatoptions+=1   " don't break line before 1 letter word
+    setlocal formatoptions+=t   " autoformat of text, but not comments
+
+    " clean out stuff we likely don't want
+    setlocal formatoptions-=2   " use indent of 2nd line for rest of paragraph
+    setlocal formatoptions-=v   " only break line at blank entered during insert
+    setlocal formatoptions-=w   " avoid erratic behavior if mixed spaces
   else
     setlocal autoindent< noautoindent<
     setlocal list< nolist<
     setlocal wrapmargin<
-    setlocal display<
     setlocal formatoptions<
-    setlocal whichwrap<
-    setlocal virtualedit<
-  endif
-
-  if b:wrap_mode
-    if g:pencil#joinspaces
-      setlocal joinspaces         " two spaces after .!?
-    else
-      setlocal nojoinspaces       " only one space after a .!? (default)
-    endif
-  else
-    setlocal joinspaces< nojoinspaces<
   endif
 
   if b:wrap_mode == s:WRAP_MODE_SOFT