Added new and unlisted commands (SHELL, SPY, NODE, LOAD, etc).
Added Ctrl-A codes for colorization/formatting.

Added SHELL command (similar to DOS command).

Slight beautification (close curly braces). Eliminate (unnecessary) assignment of file descriptor in fnopen call.

list_text_file/edit_text_file functions no longer force upper case filenames for Unix compatibility..

Modified remote SPY function to default pause line counter and disable spy output while in Ctrl-P function.

(lock is now smart enough to apply the correct lock-type based on open flags).

lock() for Unix now sets the appropriate lock type (shareable or exclusive) based on how the file was initially opened.

Added compiler error when __unix__ is defined, but not _POSIX_THREADS.