Removed (nmm) command.

The command aliased 'materials - make new with manager'.

Materials menu now looks like this:

    Red Example Score (2013) - materials

        1: magic numbers (Red Example Score)
        2: pitch range inventory (Red Example Score)
        3: tempo inventory (Red Example Score)

        material - new by hand (nmh)
        material - new for editable mainline class (nmc)

    >

So the two available commands for making new material packages are (nmh) and
(nmc).

These will probably collapse to a single (new) command at some point in future.