This commit also fixes the application of the empiricalShift in the
tracking algorithm. It is now applied the same way as the offsets,
namely: TOA + -1 * empiricalShift

The restore view button has been implemented in a custom function for temperature, pressure and toa window.

Changed label from "Point" to "Point(s)" to clearify that it is possible to select multiple points at once.

/ Changed background color of axes to white
/ Changed colormap to gray skipping the first 44 steps of 300

+ Added soundsources/colorregister package that is used to assign a color
  to a specific sound source.
+ Added an edit field to the upper and lower boundary adjustment section
+ Added a histogram plot of the TOAs
/ The soundsource color legend shows only the color of an applied sound
  source, white otherwise.

Bugfix:
  When soundsource has been applied, the zoom function was not functioning
  anymore.

Toa table:
  It is now possible to select the duplicates in the toa table, and the
  the plot will zoom to it.

Main window additions:
  - The "Reload artoa.ini" button has been introduced.

TOA window modifications:
  - The colormap of TOA now matches the nemo2profile colormap.
  - The colors of the sound sources can now be configured in artoa.ini.
  - The soundsources now are displayed as ring and in the configured color.
  - The TOA descriptions are now displayed in every third occurrence.
  - A legend with colors for the soundsources has been added to the window.

It is now possible to select TOAs and shift them by a given value.

New features:
  + If one plot changes, all other opened plots will be redrawn to
    instantly see the changes that have been made.
  + Added first version of the TOA window.
  + Added menu entry for Time of arrival editing window in the main window.