Template compiler: support for pure methods

[PostSharpBot]

The idea is to make methods like this work:

string.Format( "Method {​​​​​​​​0}​​​​​​​​.{​​​​​​​​1}​​​​​​​​ started", target.Type.ToString(), target.Method.Name) 

Rider/Resharper has a list of pure methods that we may just copy.