clear errror details on BufLeave
Merge pull request #769 from kjnilsson/master

clear errror details on BufLeave
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