adminMenu - Add Menu to Add or Edit Markers

[lambdatiger]

This PR:

1. Puts the testing menu button and the weapon testing button back at the bottom of the tests menu
2. Fixes a number of issues with admin menu markers not addressed in Markers - Fixes #649
   • Fixes marker names to be unique per side
   • Updates core marker cache properly
3. Adds buttons to edit selected marker
   • Allows admin to update marker name, color, icon, and size
4. Adds button to create new marker for a selected unit or a selected unit's group
   • Allows admin to set marker name, color, icon, and size
   • Provides option to either create marker on a unit or on the unit's group