Simplify background parsing/typechecking

This avoids a lot of needless reparses. All these reparses make the navigation extension nervous. Prior to this change, the nav bar would typically change three times when switching document.
It seems Parse() is designed to be long running, and it won't lock the UI. So there's no need to do this trickery with requesting reparses.
Merge pull request #457 from 7sharp9/vnext

Updated default stock icon to be a predefined one from MonoDevelop
Merge pull request #458 from 7sharp9/vnext

Updated template description and AspNet.Mvc version to the correct one for Mvc4
Compare bool fields by value of backing field rather than property.

When creating new projects the property value will be null, which means
the bool/string properties are never serialised.  This fixes #459
Merge pull request #460 from 7sharp9/master

Compare bool fields by value of backing field rather than property.
Merge pull request #461 from fsharp/master

fixes from master
Merge pull request #462 from 7sharp9/vnext

Updated highlight usages to use the new API
Upgrade to FSC 0.0.44
Fixes #452.
Merge pull request #463 from rojepp/fsc_0.0.44

Upgrade to FSC 0.0.44
Merge pull request #447 from rojepp/optimize_bg_parse

Simplify background parsing/typechecking
Merge pull request #464 from fsharp/master

fixes from master