Revert "If we are a VTOL, ignore ground units when moving over them. In other words, don't try to move around them, since you can fly over them."

This reverts commit 75ede1da1d77b6326b9897b59d5d394d3ef533f0.
Revert:
    Fix the SuperTransport body type to be SUPER HEAVY, not HEAVY.
    Try harder not to have them be on top of each other (only in MultiPlayer games).
    Fix explosion type.
    Fix damage calculations when they are on the ground.
    Try to better balance the Super Transport, hitpoints now at 500, Armor types changed to 35 & 20 and make weapon MG1-VTOL instead of MG3-VTOL.

This reverts commit e3279f6d033b4967b955dcaaf2ce3c5e21ed7579.

Conflicts:
	src/droid.cpp
Try to better balance Super Transport Hitpoints now at 500,
Armor types changed to 35 & 20 and make weapon MG1-VTOL instead of MG3-VTOL

refs: e3279f6d033b4967b955dcaaf2ce3c5e21ed7579
Fix Transporter types to take the same multiplier of damage as VTOLs
when on ground.

refs: e3279f6d033b4967b955dcaaf2ce3c5e21ed7579
Fix the explosion effect for the Super Transporter

refs: e3279f6d033b4967b955dcaaf2ce3c5e21ed7579
Fix message for Challenges.
Merge branch 'bugfixes' into 3.1
Fix lobby to correctly show when no games are available because of version mismatch.
Deja 'vu,  Fix picky compile issue reported by buildbot. :P
Merge branch 'bugfixes' into 3.1