Move sqlite source to a separate location, and build with
an intermediate library target. This permits us to set compile options
easier, including an important one, NDEBUG, which improves performance.
Sqlite 3.8.0.2 also includes an updated query planner which may improve
some queries, to be tested.
Keep distro packagers happy by having the option to use the system's sqlite library instead of our bundled version. Set SYSTEM_SQLITE=1 when running cmake to use the system one.
Cache the parsed navigation and airport data in a binary file to reduce
startup times and memory consumption (since only referenced FGPositioned
elements are held in memory).
Data will be reimported when the mod-time of any input file is changed.
If a global file is changed (nav.dat, awy.dat, apt.dat, etc), the cache
will be completely rebuilt, which takes approximately 30 seconds on
moderate hardware. (Future work may reduce this).
Convert the route-manager to use a flight-plan internally, and expose
flightplan, leg and procedure data to Nasal. Move the Level-D parser
into its own file.
