Initial work on NodeDiff
Moves NodeDiff, creates SequenceMatcher
Merge pull request #14 from edubkendo/master

Tests for trailing comments
remove invalid source position since invisible nodes are gone
Make sure we run specs with Java assertions enabled
src
Fix assertion issues now that we can have more null values
Merge branch 'master' of https://github.com/jruby/jruby-parser into node_diff
Skeleton for Diff functionality.
Begins documenting new classes.
Some more fallout of having nulls as potential members.  Preserve spaces is for nb pure lexing and it does not have a parserconfiguration....work around that
Merge MultipleAsgn{,19}Node into single class
GH #17. Implement stubby lambda node
Tons o position fixes in 2.0 parser and a couple in 1.9.  Spec'ing break/next/return for positions + null/no value
GH #18. Make '(' compstmt ')' create an implicit nil node which will be parent to both syntax elements '(' and ')' once that injection is added.
DRY up binary nodes with abstract base class
GH #9. Make special nodes for opelementasgn or and and.
Make newline node position in 2.0 match 1.8 and 1.9 for stmt
Merge branch 'master' of https://github.com/jruby/jruby-parser into node_diff
Begin adding specs for NodeDiff and SequenceMatcher