TST: Add xlsm to Excel parsing tests.

Added an Excel xlsm file to the excel.py reader tests.
Test for issue #4172
Merge pull request #6117 from jmcnamara/tst_excel_read_xlsm

TST: Add xlsm to Excel parsing tests.
BUG: Bug in assignment with duplicate columns in a frame where the locations
     are a slice (e.g. next to each other) (GH6120)
Merge pull request #6122 from jreback/dups

BUG: Bug in assignment with duplicate columns in a frame where the locations are a slice
BUG: Bug in propogating _ref_locs during construction of a DataFrame with dups
     index/columns (GH6121)
Merge pull request #6123 from jreback/dups_slice

BUG: Bug in propogating _ref_locs during construction of a DataFrame with dups index/columns (GH6121)
DOC: v0.13.1 doc updates
BUG: bug in DataFrame.apply when using mixed datelike reductions (GH6125)
Merge pull request #6126 from jreback/apply_issue

BUG: DataFrame.apply when using mixed datelike reductions (GH6125)
BUG" Bug in DataFrame.append when appending a row with different columns (GH6129)
Merge pull request #6130 from jreback/append_bug

BUG: DataFrame.append when appending a row with different columns (GH6129)
CLN: add comments in indexing code
CLN: comment out possibly stale kludge fix and wait for explosion
CLN: Mark if clause for handling of per-axis tuple indexing with loc
ENH: support per-axis, per-level indexing with loc[]