testcode/lib/tinyshell.c: add 'verbose' and 'cls' commands; add SP check
testcode/lib/tinyshell.c: fix error message
testcode/lib/tinyshell.c: Enable SP check only for CC65
targets. Enable 'cls' command only for Atari. Enable subdirectory
commands only for Atari and non-CC65 targets.
Fix last change: Stack check for all CC65 targets. Enable subdirectories on Apple 2.
Merge pull request #40 from groessler/something_to_pull2

testcode/lib/tinyshell.c: add 'verbose' and 'cls' commands; add SP check