excel, build: Pin xlwings wersion to 0.2.3 (0.3.0 broken!!).

* excel: Add utility funcs to open or get current Workbook, when run from python.
* docs: CHANGES mention broken behavior on speed-down to a halt.
* docs: README improve project's coordinates on landing page.
* core: Remove __init__ from cycles package.
* ci: Try fixing py27 build failing on setup.py unicode.