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.