Changed metadata command aliases.

OLD:

    metadata module - remove (mmmrm)
    metadata module - rewrite (mmmrw)
    metadata module - view (mmmv)

    metadatum - add (mma)
    metadatum - get (mmg)
    metadatum - remove (mmrm)

NEW:

    metadata module - remove (mdmrm)
    metadata module - rewrite (mdmrw)
    metadata module - view (mmmv)

    metadatum - add (mda)
    metadatum - get (mdg)
    metadatum - remove (mdrm)

The md* command namespace became available after material definition commands
change from ...

     material definition module - boilerplate (mdbp)
     material definition module - edit [mde]
     material definition module - interpret (mdi)
     material definition module - remove (mdrm)
     material definition module - stub (mds)

... to ...

     definition module - boilerplate (dmbp)
     definition module - edit [dme]
     definition module - interpret (dmi)
     definition module - remove (dmrm)
     definition module - stub (dms)

... instead.