init
Add default conveter
multi binding and type converting
fix error output
fix a bit de convertion
add tests, fix review notes
Merge branch 'develop' of https://github.com/Catel/Catel into VMtoMMapping

Conflicts:
	src/Catel.MVVM/Catel.MVVM.Shared/MVVM/ViewModels/ViewModelBase.cs
	src/Catel.MVVM/Catel.MVVM.Shared/MVVM/ViewModels/ViewModelBase.validation.cs
	src/Catel.Test/Catel.Test.Shared/MVVM/ViewModels/ViewModelBaseTest.cs
Removed unnecessary file
Several solution improvements
Final fixes for unit tests