Proposition for Unit tests more fluent syntax

[magicmoux]

Hi Hazzik,

while getting acquainted again with the project, I tried some ways that I feel would help make writing unit tests more fluent.

Could you please take a peek on magicmoux@20029ec and tell me what you think ?
The main feature is currently located in DelegateDecompiler.Tests.DecompilerTestsBase.cs as the DecompilerTestsBaseExtensions class.

Some use case examples are showcased in the NullTests.cs file

[hazzik]

Looks good. Thanks.