Unified usage of NativeMethods across all projects
Next round of DebugEngine refactoring

Mostly:
1) sealed all classes
2) reduced cross-class dependencies
3) fixed naming (as much as could)!
4) unified info about debugged process (-> ProcessInfo)
5) displaying the architecture in [Attach to...] window
6) added better input params checks
7) all classes should use common NativeMethods now

BIG THANKS to R#!