OCAThrottle: Nil the timer before produceValue is called.
OCAPredicate: Fix isEmpty on boolValue.
OCAPredicate: +isNotEmpty, +isNotEqualTo:
OCAProperty: + produceInterpolated
Merge branch 'master' of https://github.com/iMartinKiss/Objective-Chain

# By Martin Kiss
# Via Martin Kiss
* 'master' of https://github.com/iMartinKiss/Objective-Chain:
  Fix isTrue Predicate, so false is only: nil, NSNull and @NO