Use capitalized names for official functions

The distinction between "Fugitive" and "fugitive#" functions is whether
it will live in the plugin or autoload file, once the separation finally
comes to pass.

plugin/fugitive.vim

@@ -160,6 +160,10 @@ function! fugitive#is_git_dir(path) abort
         \ getftype(path.'commondir') ==# 'file')
 endfunction
 
+function! FugitiveIsGitDir(path) abort
+  return fugitive#is_git_dir(a:path)
+endfunction
+
 function! fugitive#extract_git_dir(path) abort
   if s:shellslash(a:path) =~# '^fugitive://.*//'
     return matchstr(s:shellslash(a:path), '\C^fugitive://\zs.\{-\}\ze//')
@@ -213,6 +217,10 @@ function! fugitive#extract_git_dir(path) abort
   return ''
 endfunction
 
+function! FugitiveExtractGitDir(path) abort
+  return fugitive#extract_git_dir(a:path)
+endfunction
+
 function! fugitive#detect(path) abort
   if exists('b:git_dir') && (b:git_dir ==# '' || b:git_dir =~# '/$')
     unlet b:git_dir
@@ -261,6 +269,10 @@ function! fugitive#detect(path) abort
   endif
 endfunction
 
+function! FugitiveDetect(path) abort
+  return fugitive#detect(a:path)
+endfunction
+
 augroup fugitive
   autocmd!
   autocmd BufNewFile,BufReadPost * call fugitive#detect(expand('%:p'))
@@ -296,6 +308,10 @@ function! fugitive#repo(...) abort
   return call('s:repo', a:000)
 endfunction
 
+function fugitive#Repo(...) abort
+  return call('s:repo', a:000)
+endfunction
+
 function! s:repo_dir(...) dict abort
   return join([self.git_dir]+a:000,'/')
 endfunction
@@ -555,6 +571,10 @@ function! fugitive#buffer(...) abort
   return s:buffer(a:0 ? a:1 : '%')
 endfunction
 
+function! fugitive#Buffer(...) abort
+  return s:buffer(a:0 ? a:1 : '%')
+endfunction
+
 function! s:buffer_getvar(var) dict abort
   return getbufvar(self['#'],a:var)
 endfunction
@@ -850,6 +870,10 @@ function! fugitive#reload_status() abort
   endtry
 endfunction
 
+function! fugitive#ReloadStatus() abort
+  return fugitive#reload_status()
+endfunction
+
 function! s:stage_info(lnum) abort
   let filename = matchstr(getline(a:lnum),'^#\t\zs.\{-\}\ze\%( ([^()[:digit:]]\+)\)\=$')
   let lnum = a:lnum
@@ -3080,6 +3104,10 @@ function! fugitive#cfile() abort
   return pre . s:fnameescape(fugitive#repo().translate(results[0]))
 endfunction
 
+function! fugitive#Cfile() abort
+  return fugitive#cfile()
+endfunction
+
 " Section: Statusline
 
 function! s:repo_head_ref() dict abort
@@ -3107,6 +3135,14 @@ function! fugitive#statusline(...) abort
   endif
 endfunction
 
+function! fugitive#Statusline(...) abort
+  return fugitive#statusline()
+endfunction
+
+function! FugitiveStatusline(...) abort
+  return fugitive#statusline()
+endfunction
+
 function! fugitive#head(...) abort
   if !exists('b:git_dir')
     return ''
@@ -3115,6 +3151,10 @@ function! fugitive#head(...) abort
   return s:repo().head(a:0 ? a:1 : 0)
 endfunction
 
+function! FugitiveHead(...) abort
+  return fugitive#head(a:0 ? a:1 : 0)
+endfunction
+
 augroup fugitive_statusline
   autocmd!
   autocmd User Flags call Hoist('buffer', function('fugitive#statusline'))
@@ -3165,10 +3205,14 @@ function! fugitive#foldtext() abort
   return foldtext()
 endfunction
 
+function! fugitive#Foldtext() abort
+  return fugitive#foldtext()
+endfunction
+
 augroup fugitive_foldtext
   autocmd!
   autocmd User Fugitive
         \ if &filetype =~# '^git\%(commit\)\=$' && &foldtext ==# 'foldtext()' |
-        \    set foldtext=fugitive#foldtext() |
+        \    set foldtext=fugitive#Foldtext() |
         \ endif
 augroup END