add Ref class
add ref functions to internal.h
add refivar and refcvar instructions
add references to parser and node.h
woops, add breaks
fix refcvar instruction
add CVAR_REF and IVAR_REF compile actions
add LVAR_REF and DVAR_REF to parser
add reflocal instruction
implement local refs
update dependencies for ref.c
remove debugging printf
Merge branch 'lval-references' into charlie-ruby