Implement game side of new approach in human buildable placement restrictions.

Power zones have been removed, human buildables can be placed anywehere but
there is a limit on how many can be placed in one place. To overcome this
limit, humans can build repeaters that take a number of buildables in their
range out of the calculation. Repeaters cost more and deal severe damage to
closeby structures when destroyed. Buildables that interfer with too many
neighbors will power down until a new repeater is built. Buildable replacment
takes both interference and build points into account.
Make repeaters ignore buildables that don't need a powersource.
Merge branch 'gameplay/master' into gameplay/viech
Add a brief amount of randomness to buildable blast times.
Simplify human buildable placement restriction.

Interference is treated as float, repeaters and RC don't host other buildings
but reduce the interference of all near friendly structures.
Tweak human buildable interference related values.
Merge branch 'gameplay/viech' into bots+viech

Conflicts:
	src/gamelogic/game/g_buildable.c
	src/gamelogic/game/g_local.h