Massively restructure code-base

The dual build (.NET 4.0 and 4.5) nature of Common is now accommodated
by having the .NET 4.5 projects be the main projects, with extra
projects for .NET 4.0, containing mostly links to files in the
corresponding main project.
Build version changed to 0.6.0.0
Huge restructure

Summary merge: 'beta-fixes'

* Build version changed to 0.6.0.0
* Massively restructure code-base
* Tweak project file startup setting
* Enable NuGet package restore
* Include Jetbrains attributes directly
* Make template callable from other solutions
* Fix and expand StringTree
* Allow flex objects to be given a dictionary to link
* Change test project config to AnyCPU
* Fix extra parameter bug
* Update packages
* Add StringTree, StopMonad, and OverridableBag
* Add Slacker, a lazy class
* Add OverridableList
* Clean up comments
* Automatic NuGet project stuff
* Visual Studio project file auto-insert