Improve internals of method matcher

* Fix name clash with Kernel#method
* Match full paths of node enabling next changes to fix exclusion of evaled methods from direct matches
Skip method subjects defined in blocks

* No easy way to insert mutants on these via current monkey patching
  loader
* The blocks are typically part of a method building library when those
  libraries are mutated the def/defs nodes will be part of an mutated
  block that is included in a subject.

[fix #254]
Merge pull request #255 from mbj/fix-evaled-method-matchers

Fix evaled method matchers