avoid making AIS theta calculations if they are immediately discarded
refactor ais drawing code from chcanv.cpp to ais.cpp
simplify ais rendering logic, and reduce redundant calculations
programatically support n-bells eliminating 3-8bells.wav thus reducing package size
Merge branch 'master' of https://github.com/OpenCPN/OpenCPN into reduced-bells
Correct hang with Touch Screen interface on route edit.
Correct sounding render inclusion test.
Merge pull request #146 from seandepagnier/reduced-bells

Reduced bells
Merge pull request #147 from seandepagnier/ais_optimizations

AIS optimizations
Merge pull request #148 from nkiesel/master

use wxDC#IsOk instead of (at least in wxwidget3.0 non-existent) wxDC#Ok
Correct OpenGL symbol texture loading logic
Improve performance of OpenGL raster symbol rendering
Improve OpenGL setup log messages.
Trigger controls update by a timer to improve dragging performance

On some plateform( for example my low powered netbook windows 8.1 )
dragging when grib_pi is running is slowed down by controld update
triggered directly by "setCursorLatLon" function.
To improve that, I propose to use a timer. That off course delays
the update by a few milliseconds, but should not be visible even on a
hight powered device
Remove unused variables
Improve OpenGL rendering of highlited Routes and Marks
Improve Touch screen interface user dynamics.
Correct navobj changes logic for added/deleted RoutePoints
Merge pull request #149 from Ptizef/master

Trigger controls update by a timer to improve dragging performance
Merge branch 'master' of github.com:OpenCPN/OpenCPN