Method::Signature lexing support

Method::Signatures (and MooseX::Method::Signatures) both ostensibly add keywords to the perl language, func and method.  While these add a great deal of utility for developers, it can be frustrating to use EPIC with a standard perl-only lexing scheme as that keeps outlines and other nice features of the editor from working properly.  The fix I have proposed here adds an option to the preferences pane to enable/disable this departure from Perl-only lexing, and adds the ability for the lexer to pull out func & method as if they were sub.