Catch-up commit with extensive changes

Currently testing is regarding skip changes that were nerfed to 4 max
skips with a 20 second regen per skip ammo now being slightly reverted
to 4 max skips with a 15 second regen per skip ammo. Skip units also
start with 2 skip ammo immediately after upgrading.

Scope of additional changes are sweeping, almost all completed by
ChronAberant. Major cost changes to units and technologies. Several
units with altered mechanics, many using ammo as some sort of counter.