keep name after DataFrame drop, add check_name to assert_dataframe_equal
BUG join with missing values on right (GH_2843)
Merge pull request #2965 from hayd/iss2843-left-join-on-na

BUG check both left and right indexers for None (fix 2843)
Merge pull request #2962 from hayd/issue2939_drop_loses_name_2

BUG keep name after DataFrame drop, add check_name to assert_dataframe_equal
ENH/CLN: refactor of common code from frame/panel to generic.py
         axis creation routines now commonized under _setup_axes
ENH: more methods added

PERF: was missing multi-take opportunity in reindex
      was incorrectly passing to com._count_not_none
      doing an extra copy in certain cases
BUG: reindex with called with no args will by default return a copy (fixed bug)
ENH: moved filter and added axis arg
     moved where,mask,align

TST: make reindex benchmarks longer
CLN: fixed up names for creation in panelnd.py