bugfixes for .pronsolerc handling

bugfix in .pronsolerc reading

'alias' command implemented

Prevent overwriting built-in commands with aliases, as it would delete access to the built-in command permanently

stripping code was wrong and unneeded

support for startup commands from ~/.pronsolerc 
This adds support for an alias command

Improve filename shortening algorithm. Add configurable temperature presets. Deal with missing ok after M29.