[AGIPD][LITFRM] Feat/add image selection with offline LitFrameFinder

This adds image selection with offline estimation of illuminated frames. The algorithm is implemented in separate package EXtra-redu.

This also fixes two bugs:

1. Wrong pulse selection in agipdlib.AgipdCorrections.read_file(). The extra_data.components.XtdfDetectorBase.get_array() allows to slice pulses inside in train and applies this selection to every train while agipdlib.LitFrameSelection provides flat selection over entire run.
2. Wrong estimation of the number of frames in get_trains_data() in AGIPD_Correct_and_Verify

Supposed to be widely tested on data of MID proposal 2834. See litframe report on this proposal: litfrm_p002834.csv

@schmidtp @ahmedk @kluyvert