Unified IDENTIFIER_EXTERN and IDENTIFIER_ALIAS into IDENTIFIER_ALIAS. ID_ALIAS is no more. Added {low_,}define_alias() in analogue with the other identifiers. Aliases are now used in some places where previously an identifier was copied. Added support for constants (ie aliases) referring directly to variables and functions in the surrounding scopes. A program may now be indexed on such a constant (ie alias). Added some FIXMEs. Changed API for low_program_from_function(). Disabled find_child() (could not find anything using it). Bumped build bumber since the identifier encoding has changed. Rev: src/language.yacc:1.382 Rev: src/object.c:1.277 Rev: src/program.c:1.621 Rev: src/program.h:1.233 Rev: src/version.h:1.394