Lifting CG structs, RACSequence improvements, -takeUntil: improvement

More RACScheduler work, RACTupleUnpack, bug fixes, more documentation

RACScheduler overhaul, -collect, +zip: and +combineLatest: fixes

<RACStream> improvements, thread safety fixes, -sample:, +zip:reduce:

Subscribables renamed to signals, <RACStream>, RACSequence, lifting

Add armv7s to iOS architecture list

Stable configurations

Bug fixes, -rac_performSelector:, removed generators (too buggy)

Moved Foundation categories out of RAC, added RAC() macro, removed RACAbleSelf(), bug fixes

Bug fixes, -sequenceMany: and -sequenceNext:

version 0.5.0