QGIS Plugin: AviationLatLonCalculator

Based on previous plugins related to calculating geographical coordinates given in various ways, it's time to combined all them into one handy plugin. In this case I will also use enhanced version of aviation gis tools scripts.

Basically, the logic is very much the same as in 'separated' plugins which deal with this issue,  so there will be not too much comments this time. I only share some code to discuss main differences when I use classes from aviation_gis_tools2 module.