Initial check-in

Simplified the code:
 - Only add Smalltalk enumeration, don't include Ruby's Enumeration
methods
 - Only focus on NSArray
Added:
- NSArray>>#doWithIndex:
- NSArray>>#do:separatedBy:
- NSArray>>#collectWithIndex:
- NSArray>>#detect:ifNone:
- NSArray>>#detectIndex:
- NSArray>>#rejectWithIndex:
- NSArray>>#selectWithIndex: