Add more specific file pattern matching for fsharp

To avoid accidentally matching and applying our functions on .fsproj
files
Added BufEnter trigger to redisplay erors

BufLeave does a decent job of disabling error displays (not perfect, but
BufHidden doesn't seem to do what I thought it did).  But, once we
bufleave hide the errors, they never come back.  This BufEnter trigger
will cause them to redisplay.
Merge pull request #771 from sillyotter/master

Fixes for #763 and #762
Update AppVeyor emacs download to 24.4
Correct AppVeyor unzip logic
Upgrade ExtCore reference to 0.8.43 in MonoDevelop.FSharpBinding project. The new version references FSharp.Core 4.3.0.0, which should fix assembly-resolution issues some users were seeing on Windows.
Merge pull request #775 from jack-pappas/extcore-0_8_43

Upgrade ExtCore reference to 0.8.43 in MonoDevelop.FSharpBinding project
rework vim plugin to integrate into syntastic plugin

Instead of reinventing on-the-fly code/type checking fsharp-vim
can reuse the existing functionality of the syntastic plugin.
adjust Makefile with new files
<leader>i does type checks only
fix error highlighting
write logfiles in debug mode only
update README
README: autocommand for fsharp files only
close scratch window after leaving insert mode
README: add hint to debug mode
type checking should map to <leader>t instead