* commit 'v0.7.0rc1-205-g8610be5': (22 commits)
BUG: open file in Python 3 with given encoding
BUG: actually pass encoding to UnicodeWriter
BUG: use UnicodeWriter on Python 2.x
TST: fix vbench per Series constructor api change
TST: fix numerical stability issue present on certain platforms
DOC: readme update
TST: fix debian / 2.5 test
BUG: always return True for onOffset for regular DateOffset, closepandas-dev#770
Fixed regression with Panels caused by NDFrame not checking if it was DataFrame before assuming it had a 'columns' attribute.
Tests for 'mixed depth' hierarchical columns. Tests for getting, setting, dropping and popping columns from dataframes which have MultiIndexed columns containing some empty strings at the lower levels, by indexing with only the upper levels. Also modified NDFrame._set_item to use the same shorthand.
Modifications to column-hierarchical behaviour as per "'Mixed depth' hierarchical column labels'" discussion on pystatsmodels. If column label tuples contain only empty strings at the lower levels, allows the DataFrame to be indexed with only the higher levels. So for example if a column has the hierarchical label ('a','',''), and there are no other columns with 'a' at their top level, then this change allows the column to be pulled out with df['a'], rather than df['a','','']. It also names the resulting series 'a'. The use case for this is when some columns have a deeper hierarchy than others, and you want to treat the shallower columns as if the lower levels of the hierarchy weren't there.
STY: fit in 80 columns
Add sheet_names property to ExcelFile, with tests
Put ExcelWriter in pandas namespace
TST: test coverage
TST: test coverage, pep8
TST: skip test on Python 3
TST: use BytesIO with encoded text for python3
DOC: update docs to reflect new PyData home