I made the path finder faster

[laverdet]

Two things in this PR.. The first is some optimizations to the code, mainly removing pointer indirection.. basic stuff. The second is an optional second pass compile using the profile-guided optimization features of GCC or Clang. To run this second stage navigate to the native directory and run ./run-pgo. It will compile a special version of the path finder module which collects profiling information. Then it runs that with some sample terrain data for some time (maybe 30 seconds). Finally it compiles again using that data to direct compiler optimizations.

After both changes you can expect a performance improvement of 5-10% on an optimized build. The results of the path finder remain identical.

[laverdet]

@artch I seemed to have left out the final line of run-pgo:
mv build/Optimized/native.node build/Release/

You should add that to the end of the run-pgo script or driver will still include the non-optimized "build/Release/native.node"

Sorry about that!

[laverdet]

--- a/native/run-pgo
+++ b/native/run-pgo
@@ -12,3 +12,5 @@ make V=1 BUILDTYPE=Optimized -C build
 echo "Re-running..."
 node profile.js Optimized >/dev/null
 echo "Looks good. Replacing release with optimized."
+mkdir -p build/Release
+mv build/Optimized/native.node build/Release/

[artch]

Yeah, I figured out. It actually has to be integrated in the build process anyway, without using globally installed node-gyp and stuff.