Fix/map feature

[dforsi]

This PR:

• adds the transmitters.csv file to the resources and converts its encoding from ISO-8859-1 to UTF-8 to show the accented letters
• modifies the table of map items settings
  • to right align all numeric cells
  • to use a QSpinBox for the "Filter Distance" cells
  • to do a case insensitive sorting of column containing the labels

For the QSpinBox of "Filter Distance" I set a minimum value of zero and a maximum of 10000 km; I used setSpecialValueText() to replace the zero with one space so the the look of the table isn't too much different from before (we can't use an empty string or a nullptr because they disable the replacement).

The case sensitive sorting is needed otherwise "Airport" and "Airspace" were coming after APTdemod.