Two items prevented python3 compatibility:
* Breakage of ASCII codec due to non-ascii characters in README: https://github.com/biopython/biopython/issues/1649
* The outdated dependency: print/py-reportlab1 instead of the modern version 3.X print/py-reportlab
Port changes:
* USES=python:2.7 -> USES=python
* Add pre-configure that clears the README file
* Add LICENSE/LICENSE_FILE
Testing:
* Ran the tutorial testcase http://biopython.org/DIST/docs/tutorial/Tutorial.html,
particularly pdf writing through print/py-reportlab worked fine.
Asked the upstream to clarify the acceptable dependency version: https://github.com/biopython/biopython/issues/1650
Approved by: portmgr blanket (unbreak for python3; add license)
