TECO-64 version 200.20.0

This release mostly involved the creation of test scripts, and also a Perl script used as a test harness. These are not necessary to run TECO, but are used as a smoke test to confirm basic functionality. These are only the initial set of scripts; there will be more provided in future releases.
The CTRL/T command to read input w/o waiting (non-blocking I/O) now requires display mode in order to function. A DPY error will be issued if this is not the case.
Processing of DEL characters when in non-display scope mode has been improved (especially when deleting LF and CR).
EZ command has been added to replace ::EG command.
At-sign form of "=" command now allows string building characters.
Added -K debugging option for saving keystrokes to file.