pep8 cleanups
fix bug in irregularlysampledsignal __eq__
fix initialization of recordingchannelgroup channel_indexes and channel_names
fix neo.test.tools handling of some assert_array_equals corner cases
implement merge method in all relevant classes
fix attributes not being copied on mathematical operations
fix bug in eventarray __repr__ for python 3
add __repr__ to epocharray
implement mathematical operators for irregularlysampledsignal
fix bug with rescale in irregularlysampledsignal
improve segment take_[]_by_[] methods
fix segment all_data python 3 compatibility
fix bug in _new_spiketrain
add force argument to create_many_to_one_relationship to overwrite existing relationships
support annotations in segment.filter
improve unittest coverage for neo core