Merge pull request jspahrsummers#102 from k06a/extnil-impovement

Implemented self method on EXTNil

Various warning fixes

Moved experimental features to a separate branch

xcconfig updates, add @collectionKeypath

++xcconfigs, README updates

Build settings fixes, disable -Wshadow with @strongify

Fix @synthesizeAssociations overwriting each other, ++xcconfigs

Fix buffer overflow in ext_copyPropertyAttributes()

Fix SEL casting errors on Xcode 4.6

Added armv7s to iOS architectures