Added basic support for overloaded verbs.

Overloaded verbs represent overloaded methods marked with VerbAttribute.
Assuming they can be used with different number of arguments and/or
argument types (as far as C# allows).
Added several other rules of locating the correct verb.
Reorganized code to better fit the task.
Removed useless line of code.
Merge pull request #22 from mikalai-kardash/master

Added ability to select preferred verb instead of the first one.