`mccode-antlr config` is not fully functioning

[g5t]

The sub-commands of mccode-antlr config , set and unset do not modify the configuration because they do not write changes made to the in-memory configuration to file.

Until this is fixed, the ability to change configuration keys is only possible through directly editing the configuration file -- which itself might require first a call to mccode-antlr config save -v in order for a copy

1. a copy to exist on disk (save) and
2. the user to know where it is located (-v).