Added new Features: Find all references, highlight usages, and rename refactoring

Also reverted to single instance of the F# mime type until the old one
is removed from MonoDevelop.  Changing the mime type affects the
parsing of files because the first mime type registered for the .fs
extension takes precedence and the ones we define here in the binding
don’t take effect.
Changed highlight usages to work on a background thread rather than UI, also added disposal cancelation
Merge branch 'master' of github.com:fsharp/fsharpbinding
Fixed number of parameters on GetReferences
Renamed getFileAndArgsFromProject to getCheckerArgsFromProject
Refactored GetReferences to use the correct number of checker parameters
Added GetSymbol function to the language service

Refactored naming of untyped parse info to match new naming in
FSharp.Compiler.Service.  Also exposed underlying CheckFileResult
Merge pull request #321 from 7sharp9/base

Minor improvements to Language service
Fix for #280
Merge pull request #322 from 7sharp9/280

Fix for #280
Added monospace for code elements in tooltips
Cleaned up tooltips

Removed formatwithheader
Split tooltip into signature and comment rather than aggregating
Removed complicated splitting of tooltip pieces because of aggregation
of the tooltip and comment.
Added negative clauses, rather than only checking -1

Also ensured signature and comments were trimmed.
Moved the option type wrapping into Tooltip helpers(Having the failover
return the original summary causes parameter help to be massive, better
to return None when there is no parameter xmldic)
Simplified Parameter Data provider

Also reduced the tooltip lookups by retrieving summary and comments
only once.
Merge pull request #323 from 7sharp9/tooltipcleanup

Tooltip clean up, and fixes.
Merge branch 'master' of github.com:fsharp/fsharpbinding
Disabled the Reference finder for now
Merge pull request #310 from 7sharp9/master

Added new Features: Find all references, highlight usages, and rename refactoring