MM geometry fixes

This MR deals with:

1. new stations.v2.08.xml/stations.v2.08_Aside.xml:

• MM: The proper values of the top/bottom frames (ie frame+empty space due to missing strips) are updated.
• MM: The active areas are expanded by 1pitch in total, to include the whole strips in the active volume.

2. In the MMReadoutElement:

• The active areas are moved by half difference of the top/bottom frames and are placed at the center of the quadruplet.
• localToGlobalCoords() returns correctly the positions in the global ATLAS reference frame

3. In the sTgcReadoutElement:

• add stripGlobalPosition() returns the strip position in ATLAS global reference frame
• localToGlobalCoords() returns correctly the positions in the global ATLAS reference frame

4. In Micromegas.cxx / sTGC.cxx of the MuonGeoModel, the correct frame parameters are initialized and used depending on the module.

adding @alaurier, @rosati and @nkoehler