withMacro and withMacroRec pattern classes
Identity rules
Fix bug regarding withMacro inside delimiters
Rename withMacroRec and withMacro to invoke and invokeOnce
Add throwSyntaxCaseError
Change identity rule form.
Allow the pattern environment to be extended by invoked macros
Refactor loadPatterns to 1 pass. Implicitly call invoke for custom classes.
Merge branch 'pr/244'

Conflicts:
	src/patterns.js
build
Match underscores literally in a literal group.
Fix for nodejs requires

Added back in a require for escodegen that enables requiring .sjs files from within node
Merge pull request #254 from natefaubion/uscore-lit

Match underscores literally in a literal group.
Merge pull request #256 from matthewrobb/patch-1

Fix for nodejs requires
build
Correct typo pattStx -> patt
Move cloneSyntaxArray to syntax. Rename joinSyntaxArr to joinSyntaxArray
Clone repeater match syntax when transcribing.
Merge pull request #262 from natefaubion/patt-typo

Correct typo pattStx -> patt
Merge pull request #263 from natefaubion/repeat-delim

Clone repeater match syntax when transcribing