Expand functionality of <CR> mapping (#1011)

* Define default values for new variables governing new "Default Open".

"Default Open" means to open a file with the Enter key (which of course
can be changed.) The key can be changed in the vimrc, and there is a
variable for specifying the Opener parameters for opening the node. This
lets the user decide whether Enter (or another key) will open a file in
the current tab or a new one, and whether or not to open the file again
in the tab or jump to a window where the file is already open.

* Remove the old mapping for <CR>, a duplicate of 'o'.

<CR> will be defined like all the other keys, in plugin/NERD_tree.vim

* Assign functions to the new <CR> key mapping.

Three separate functions handle directories, files, and bookmarks.

* Rename variables: NERDTreeCustomOpen and NERDTreeCustomOpenArgs

* Add documentation for NERDTreeCustomOpenArgs and NERDTree-<CR>.

* Make key mapping variables be indexed in the Vim help

* Remove angle brackets from <CR> to see if help navigation improves.

* Rename functions from defaultOpen... to customOpen...

* Use separate options for file and directory nodes.

* Update documentation for separate file/directory options.

* Update version number and change log.

* Change CR to <CR> in help tags.

* Fix missing backtick in patch number.

* Update the quickhelp text.

* Update Pull Request template.

* Update change log with simpler formatting of patch number.

* Get NERDTree version number directly from CHANGELOG.md

* Reformat the lists of contributors in the Change Log.

* Initialize the version text, just in case the while loop finds nothing.

autoload/nerdtree.vim

@@ -3,8 +3,19 @@ if exists("g:loaded_nerdtree_autoload")
 endif
 let g:loaded_nerdtree_autoload = 1
 
-function! nerdtree#version()
-    return '5.1.3'
+function! nerdtree#version(...)
+    let l:changelog = readfile(expand("<sfile>:p:h")."/CHANGELOG.md")
+    let l:text = 'Unknown'
+    let l:line = 0
+    while l:line <= len(l:changelog)
+        if l:changelog[l:line] =~ '\d\+\.\d\+'
+            let l:text = substitute(l:changelog[l:line], '.*\(\d\+.\d\+\).*', '\1', '')
+            let l:text .= substitute(l:changelog[l:line+1], '^.\{-}\(\.\d\+\).\{-}:\(.*\)', a:0>0 ? '\1:\2' : '\1', '')
+            break
+        endif
+        let l:line += 1
+    endwhile
+    return l:text
 endfunction
 
 " SECTION: General Functions {{{1

autoload/nerdtree/ui_glue.vim

@@ -14,6 +14,9 @@ function! nerdtree#ui_glue#createDefaultBindings()
     call NERDTreeAddKeyMap({ 'key': '<2-LeftMouse>', 'scope': "Bookmark", 'callback': s."activateBookmark" })
     call NERDTreeAddKeyMap({ 'key': '<2-LeftMouse>', 'scope': "all", 'callback': s."activateAll" })
 
+    call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapCustomOpen, 'scope':'FileNode', 'callback': s."customOpenFile"})
+    call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapCustomOpen, 'scope':'DirNode', 'callback': s."customOpenDir"})
+    call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapCustomOpen, 'scope':'Bookmark', 'callback': s."customOpenBookmark"})
 
     call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapActivateNode, 'scope': "DirNode", 'callback': s."activateDirNode" })
     call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapActivateNode, 'scope': "FileNode", 'callback': s."activateFileNode" })
@@ -76,6 +79,35 @@ endfunction
 "SECTION: Interface bindings {{{1
 "============================================================
 
+"FUNCTION: s:customOpenFile() {{{1
+" Open file node with the "custom" key, initially <CR>.
+function! s:customOpenFile(node)
+    call a:node.activate(s:initCustomOpenArgs().file)
+endfunction
+
+"FUNCTION: s:customOpenDir() {{{1
+" Open directory node with the "custom" key, initially <CR>.
+function! s:customOpenDir(node)
+    call s:activateDirNode(a:node, s:initCustomOpenArgs().dir)
+endfunction
+
+"FUNCTION: s:customOpenBookmark() {{{1
+" Open bookmark node with the "custom" key, initially <CR>.
+function! s:customOpenBookmark(node)
+    if node.isDirectory
+        call a:node.activate(b:NERDTree, s:initCustomOpenArgs().dir)
+    else
+        call a:node.activate(b:NERDTree, s:initCustomOpenArgs().file)
+    endif
+endfunction
+
+"FUNCTION: s:initCustomOpenArgs() {{{1
+" Make sure NERDTreeCustomOpenArgs has needed keys
+function! s:initCustomOpenArgs()
+    let g:NERDTreeCustomOpenArgs = get(g:, 'NERDTreeCustomOpenArgs', {})
+    return extend(g:NERDTreeCustomOpenArgs, {'file':{'reuse': 'all', 'where': 'p'}, 'dir':{}}, 'keep')
+endfunction
+
 "FUNCTION: s:activateAll() {{{1
 "handle the user activating the updir line
 function! s:activateAll()
@@ -84,15 +116,16 @@ function! s:activateAll()
     endif
 endfunction
 
-" FUNCTION: s:activateDirNode(directoryNode) {{{1
-function! s:activateDirNode(directoryNode)
+" FUNCTION: s:activateDirNode(directoryNode, options) {{{1
+" Open a directory with optional options
+function! s:activateDirNode(directoryNode, ...)
 
     if a:directoryNode.isRoot() && a:directoryNode.isOpen
         call nerdtree#echo('cannot close tree root')
         return
     endif
 
-    call a:directoryNode.activate()
+    call a:directoryNode.activate((a:0 > 0) ? a:1 : {})
 endfunction
 
 "FUNCTION: s:activateFileNode() {{{1