Optimize showMessage
Modify showMessage

It now requires the options list to have the number of options at
the front.  You can also pass the default argument in A.
Minor optimizations in castle.asm and hello.asm
applib(showMessage): Correct behavior in case of out-of-bounds default option
Minor optimization in applib.asm
Merge pull request #50 from KnightSoft/showmessage

Merge Showmessage branch