Merge pull request #114 from seandepagnier/optimum-merging

Optimum merging -- lots of incremental optimizations
Improve vector chart depth sounding display performance
3.3.1713
specialize route and waypoint rendering for opengl, and simplify logic
remove unused member variable
fix incorrectly calculated coordinates for rotated and skewed transverse mercator charts
reduce cpu usage when rendering status bar (needed because gtk+ and cairo is very slow at this)
optimize rendering chart outlines for opengl
add routines for plugins to cache vertex positions in display lists or vbos
remove global stencil flag, and update plugin chart rendering to use new flag
fix zoom to cursor problem
add opengl-specific options dialog
simplify and optimize gshhs rendering, and use our routines so any projection can be usedit can be used
defer loading portaudio until a sound is played (greatly speeds up program load time)
logic corrections for updated floating compass
initialize cm93 chart outline display list to 0
use strokelines for rendering tracks for efficiency and nicer display
allow smooth zoom/pan with zoom to cursor (why was this disabled?)
skew and course-up corrections
optimize refresh logic for updating ships