Scissors v0.2.0 bug fix and fork integration release

This version integrates improvements and changes from the various forks of Scissors and fixes a few bugs. Most functionality works well, although there are still some rough edges (such as the crop() method, which works only on certain PDFs). A test suite has been added, but it mostly tests that the PDFTK commands have been executed, and do not verify the correct result. In sum: lots of room for improvements remains until we can release v1.0.

Please test and continue to contribute...