WIP: Resolve "Memorize sets of motor positions (port from BM32)"

Closes #1623

Proposed API

Class to save positions of motor sets in settings.

Motor sets are called profile, managed with:
        pdef, plist, pdel
Positions are managed with:
        mpos, spos, dpos, gpos
        
Usage:
- pos = mpos(profile_name)      # profile_name is optional
- pos.plist()                   # list all defined sets of motors (name + motors)
- pos.pdef(name, *motors)       # define a new set of motors
- pos.pdel(name)                # delete a set of motors
- pos.mpos(position_name, profile_name)       # store positions of motors
- pos.spos(name)                # show stored positions matching name pattern
- pos.dpos(*name)               # delete stored positions
- pos.gpos(name)                # go to stored position = move all motors from the set to stored position