Add path manipulation commands AppPath, RemPath, PrepPath
Robert Sprowson authored
This triplet of commands allows obey files and similar to 'edit' path variables
such that they don't grow ever longer each time the obey file is run, and to
ensure it is possible to get the priority of elements on the path as desired.

Removed a malloc/free from *SafeLogon; the other commands all assume one OSCLI
buffer of space is available on the stack and use an automatic variable.
695b533e