Indexing

[briantoby]

Summarizing changes so far in this branch

GSASIIdataGUI.py

• make sure initialization of self.HKL (G2frame.HKL) is to np.array([])
  (I saw an error where plotting failed due to trying to perform G2frame.HKL.T on a list)
• Clear status bar before display of data tree items
  (prevents stale msgs from persisting)
• Move plotting into UpdateUnitCellsGrid

GSASIIpwdGUI.py

• initialization of G2frame.HKL always as np.array()
• OnTryAll: avoid error if OnHklShow returns an empty list or ssopt['SgResults'] is empty
• onHklShow: extensive comments; move SetItemPyData(...peaks) to where peaks is changed
• lines 6088 to 6594: extensive GUI reorg
• 6608: end UpdateUnitCells with a call to OnHklShow
  so that that the displayed cell/sym is what is shown on plot

GSASIIpwdplot.py

• more comments
• 2448-2456: even if there are no peaks, still show reflections

[briantoby]

This work is intended to address #44 but is paused as Bob has been working on the same things.