Update txsgui Diff Plot

This Merge Request builds on (and includes) MR !12 (merged) and adds a plot widget to display the diffs that supports updates and user interaction.

It also makes some changes to txsgui.py/.ui to make it work with current txs version.

Some screeshots:

The parameters I used with ./txs/tests/sample_data/bliss/dye1/dye1_0002/scan0012 data for testing it: txsgui_pars.ini

And the patch for mocking a "live" update of the data:

+++ b/txs/live.py
@@ -41,7 +41,7 @@ def ana(folder, ref_delay, ai=None, extension='h5', qnorm=None, qlim_azav=None,
         norm=None, qlim_datared=None, shots=None, use_ratio=False,
         red_chi2_max=None, pts_perc_max=None, log='id09', do_azav=True,
         do_datared=True, sleep_azav=0.5, sleep_datared=0.1, sleep_save=1,
-        sleep_loop=10, plot=False, track_abs=False, track_diff=False,
+        sleep_loop=1, plot=False, track_abs=False, track_diff=False,
         track_diff_t='last', qmon=None, result_callback=None,
         track_abs_qmon=None, track_diff_qmon=None,
         progress_callback=None, debug=False, verbose=True):
@@ -223,6 +223,13 @@ def ana(folder, ref_delay, ai=None, extension='h5', qnorm=None, qlim_azav=None,
                                            return_fnames=True,
                                            verbose=True)
 
+                # patch to load file one by one:
+                if len(fnames) > 1:
+                    imgs, fnames = load_images(folder, extension=extension,
+                                            exclude=([] if exclude is None else list(exclude)) + list(fnames[1:]),
+                                            return_fnames=True,
+                                            verbose=True)
+
                 if len(imgs) == 0:
 
                     if first_attempt: