Fix project

The VS11 could not compile.
Enforcing compilation warnings
Port CodeFormatting to F#
Remove dependency on FantomasOptionsPage
Fix rebase side-effect

FSharpVSPowerTools.csproj could not be loaded anymore (invalid XML)
Fix rebase side-effect 2
Merge remote changes from 'upstream' to 'master'
Merge & remove annoying F# warnings

* The annoying warning is the one labeled #52
Fix modal dialog display

Visual Studio unfortunately must be aware of any model dialogs while
they are visible.  This changes the Rename dialog to call into the
EnableModeless API as appropriate during display
Merge pull request #83 from vasily-kirichenko/master

Use InteractiveChecker.InvalidateConfiguration instead of InvalidateAll if a project changed
Merge pull request #85 from jaredpar/fixes-modal

Fix modal dialog display
Merge pull request #67 from OkayX6/master

Port CodeFormatting from C# to F#
Minor cleanups
Reinforce code style take 1

- Use 'x' for instance names consistently
- Use 'as self' to refer to instance names in constructor declarations
Reinforce code style take 2

- Module functions are camelCase
- Type members are PascalCase
Reinforce code style take 3

- Remove unused parameters (which have '_' prefix)
- Type annotation should use ': ', not ':' or ' : '

Address #86
Add a contribution guideline