Issue #18: Symbolic Cross-Referencing in Headers
Issue #20: Recursive Area Filename Availability Mechanism

Added cross-referencing to command.area.asm, made cosmetic changes, and resolved issue #20 while I was in there.

This is not expected to be the final commit for issue #18, but is expected to be the final commit for issue #20.

Files impacted by this commit:

	code/commands/command.area.asm