improve zooming functionallity for wheel and toolbar
use sse2 cflag rather than sse
Merge pull request #116 from seandepagnier/optimum-merging

Optimum merging -- a few more updates and corrections
3.3.1715
Correct and harmonize raster chart region calculation for skewed charts.
Set OpenGL texture compression options to default "OFF"
Merge branch 'master' of https://github.com/OpenCPN/OpenCPN into mingw
minor fixes for mingw..  NSIS template change should not be merged