Major GUI rearrangement

[aleksejs-fomins]

• Consider having only one original axes, with other windows being only auxiliary buttons, sliders and tables
• Group preprocess and postprocess controls into separate windows.
• Group related buttons into panels within windows
• Decide if filtering is still needed after graphical selection works. If yes, create separate button for trace and point-filtering. Using drop-down menu turns out to be annoying
• Introduce progress bars for all tasks that take time
• Disable interactions with GUI during video processing and time-merge stages
• Disallow traces-specific buttons to be pressed during ROI-view. Emphasize via button location