Added TODOs on System.Progress
Clean up from static analysis
Merge branch 'Fix' into Develop

* Fix:
  Improved exceptions on SemaphoreSlim constructor
Commented some quirks
Marked TODOs in FolderEnumeration
Clean up from static analysis
Merge branch 'Fix' into Develop

* Fix:
  Updated Reame (fix)
  Updated Readme
  Made IExtendedGrouping variant when it can be
Merge branch 'Fix' into Develop

* Fix:
  Linq refresh from Mono and other clean up
  Use IReadOnlyList in ElementAt*
Merge fix
Merge branch 'Fix' into Develop

* Fix:
  Reviewed use of "internal"
FIx for MemberExpression.EmitPropertyAccess.

Fixed incorrect else clause as pointed by siteatis
Merge branch 'Fix' into Develop

* Fix:
  FIx for MemberExpression.EmitPropertyAccess.
Merge

Note: this branch does not build ConcurrentDictionary is half baked.