Fix magnetic heading display setting persistency
Correct GRIB PlugIn for No-GL build rules
Correct deferred internal triangle tesselator for No-GL build rules
Correct PlugIn API for No-GL build rules.
Merge branch 'master' of https://github.com/OpenCPN/OpenCPN into mainline

Conflicts:
	include/mygeom.h
	src/mygeom.cpp
	src/navutil.cpp
	src/pluginmanager.cpp
	src/tri.c