unit_carrier_drones.lua: fix case of crash when drone was destroyed in same frame as when nanoframe is created.
& fix case where carrier suddenly pause spawning drone until next reload while 1 drone was destroyed while being built

Crash happen because UpdateCoroutine() accidentally skipped 1 frame when 2nd drone was created. This skipped frame give some chance for NIL to pass.
Can happen by burning Armcarry while it spawn 2 drone in succession.
CrudePlayerList & DeluxePlayerList: ops, remove redundant check added in https://github.com/ZeroK-RTS/Zero-K/commit/36eb7e3372fba37594d9e9e29bfcb5919e41e0ad
which is not needed because Chili already avoid steal mousewheel if no scrollbar is present
Merge pull request #59 from xponen/carrier_drone_crash

fix case of Carrier drone crash