cleanup

Epochs: integrate ._reject_setup() into .__init__()
ENH: Epochs

Add custom epoch rejection time interval (reject_tmin and reject_tmax
kwargs).
FIX: reject time window

 - DOC
 - kwarg order
 - don't raise an error for reject_tmin == tmin and reject_tmax == tmax
 - revert to using ._reject_setup() from .__init__()
TST : improve testing of reject_tmin / tmax
Merge branch 'master' of github.com:mne-tools/mne-python