Added -reduceAll and -reduceAny in #660

Only accepts a RACTuple of NSNumbers
Gone for @kastiglione's naming
Managed to invert the operators with a find & replace
Fixed some style issues for reduceByAnd/Or
Fixed indentation in reduceByAnd
Change reduceByAnd/Or to just and/or
Fix typo in operation name string
Punctuating comments
Removing compiler-inferred return types
Fix additional typo
Added Assertion for 0-Tuple for -and, -or
Improved language in header comments for -and/-or
Assert wording consistency for -and/-or
Pluralisation for -and/-or asserts
Boxing is implied, all signals return objects
Refactor -invalidateGlobalRefIfNoNewSubscribersShowUp

Specifically, avoid block allocations (by avoiding variable capture), and only check RACActiveSignals once per run loop iteration.
Don't allocate RACSignal->_subscribers until needed
Avoid -tupleByAddingObject: in zip/combine

This reduces the number of allocations performed as the number of streams grows.
Factor out +zip: and +combineLatest: logic into 1 method
Manage active signals in a lock-free way