Use a void* as the KVO context. Saves us those horrible typecasts and makes the code more readable. Also, strings may get uniqued, so if someone were to use the same string (unlikely in this case), they’d get the same pointer value.
Check return value of init.
More use of void*, this time for associated object.
Move check out of header so people using -fobjc-arc in non-ARC projects can still use this class.
Merge pull request #2 from uliwitness/pullrequests/noprefixheader

Make this compile without Foundation in the prefix header.
Merge pull request #3 from uliwitness/pullrequests/paranoia

Fixes for issues that would probably never crop up in practice
Pull changes from Uli, close #4

Conflicts:
	NSObject+JCSKVOWithBlocks.h
Merge branch 'master' of https://github.com/Abizern/KVOWithBlocks

# Via Abizer Nasir (3) and Uli Kusterer (1)
* 'master' of https://github.com/Abizern/KVOWithBlocks:
  Move check out of header so people using -fobjc-arc in non-ARC projects can still use this class.
  More use of void*, this time for associated object.
  Check return value of init.
  Use a void* as the KVO context. Saves us those horrible typecasts and makes the code more readable. Also, strings may get uniqued, so if someone were to use the same string (unlikely in this case), they’d get the same pointer value.