EXTAspect: support getters & setters at the same time

Don't always break out of the "find getter and setter" loop as soon as one
of them is found; if there are advices for both, loop needs to keep
looking for the other one.

And a unit test for it.
Merge pull request #39 from lpgagnon/master

EXTAspect: support getters & setters at the same time
++xcconfigs
Remove all experimental/unsupported modules
Remove experimental features from README
Fix unit testing in Xcode 5
Mention the experimental branch in the README
Fixes to ext_globalMethodSignatureForSelector()

* Fixed problem with cache (#43)
* Now also searches through optional protocol methods, if needed (#42)

Added tests for both.
Changes per @jspahrsummers review

Squash before merging into master
Merge pull request #44 from claybridges/clayb-global-sig

Fixes to ext_globalMethodSignatureForSelector()
Add instructions for including libextobjc in a project
Link to submodule documentation too
Updated ReadMe.
Fixed typo in ReadMe.