consolidate and optimize clipping region logic
code formatting (whitespace change)
improve opengl extension function handling, and opengl setup
change GL_CLAMP to GL_CLAMP_TO_EDGE as the older setting is deprecated
grib plugin: add tooltip and improve warning message
use opengl texture for raster symbols if rectangle textures are supported
use std::string in nmea sentence parsing

This greatly reduces idle cpu (and therefore powerconsumption) noticed mostly
 on slow cpu's like raspberry pi, because unicode conversions per character are no longer performed
fix issues detecting serial ports, this fixes issue which used to crash on raspberry pi
remove unused file
logic improvements and remove duplicated glenable  and unused code
optimize light sectors: remove duplicated initial point, and use float since double is not needed here
split rendering of overlay objects for opengl optimizing ownship rendering
correct rotated coordinate calculation, and optimize grid draw for opengl allowing rotated viewports
fix crash at certain rotation angles for journeyman style
scale bar rendering for rotated viewports
use a textures to render emboss indicators