Fixes and tweaks

- Fix: Fixed stimuli different, good for Cosyne 2013.
- Fix: Show the legend or not in plot_likelihood_correctlycuedtimes
- Fix: Cleaned get_network_response_bivariatefisher
- Fix: Plot_coverage_feature_space uses specific ticks now, prettier.
- Fix: Corrected create_mixed
- Fix: pcolor_2d_data returns figure handles.
Launchers for Mixed population Volume

- Added: Created launchers for 3D volume search for FI Theo+var for a mixed population code. Doesn't work that well but oh well.
- Added: 3D plot for Mixed population runs.
- Fix: some tweaks in launcher_reload_fisher_information_param_search
Try to look at Fisher information for two stimuli in 1D.

- Add: Some code (but wrong) looking at effect of one stimuli onto the encoding precision of another. Wrong math, to be redone shortly.