Added -extractBufferedDataFromFile:error:action method to allow buffered reading of archived files (Issue #4)
Rearranged callback methods
Updated BufferedReadCallbackProc so it doesn't copy the data, and added a new unit test which generates a ~20 MB text file, then uses the rar command line tool to archive it and then extract it in a buffer (Issue #4)
Decreased size of large text file, so that unit test execution doesn't fail out on Travis CI
Merge remote-tracking branch 'origin/v2.3' into issue4
Merge branch 'v2.3' into issue4
Merge branch 'issue4' of https://github.com/abbeycode/UnrarKit into v2.3

Conflicts:
	Classes/URKArchive.h
	Classes/URKArchive.mm
	Tests/URKArchiveTests.m