share/simple_xls.py: updated docstrings.
ChIP-seq/make_macs2_xls.py: 0.2.1, significant refactoring.

Move functionality into new class and functions, add tests and switch to
new simple_xls.py module to generate spreadsheet.
ChIP-seq/make_macs2_xls.py: updated and extended tests (including MACS 2.0.10.20131216, with and without --broad option).
ChIP-seq/make_macs2_xls.py 0.2.2: extract command line and detect if --broad was used (don't generate output in this case).
ChIP-seq/make_macs2_xls.py: remove "FDR" from legends text.
ChIP-seq/make_macs2_xls.py 0.2.3: only sort on fold enrichment column.
ChIP-seq/make_macs2_xls.py 0.3.0: substantial update to deal with MACS2 --broad output.
ChIP-seq/make_macs2_xls.py 0.3.1: if "command line" is too long then split over multiple cells.
share/simple_xls.py 0.0.8: add some limits as constants in the 'Limits' class.
ChIP-seq/make_macs2_xls.py 0.3.2: if number of records exceeds row limit then split over multiple sheets.