Initial code for boids v2

Too many new features to list! But here are the biggies:
- Boids can move on air and/or land, or climb a goal object.
- Proper interaction with collision objects.
	* Closest collision object in negative z direction is considered as ground.
	* Other collision objects are obstacles and boids collide with them.
- Boid behavior rules are now added to a dynamic list.
	* Many new rules and many still not implemented.
	* Different rule evaluation modes (fuzzy, random, average).
- Only particle systems defined by per system "boid relations" are considered for simulation of that system.
	* This is in addition to the boids own system of course.
	* Relations define other systems as "neutral", "friend" or "enemy".
- All effectors now effect boid physics, not boid brains.
	* This allows forcing boids somewhere.
	* Exception to this is new "boid" effector, which defines boid predators (positive strength) and goals (negative strength).
	
Known issue:
- Boid health isn't yet stored in pointcache so simulations with "fight" rule are not be read from cache properly.
- Object/Group visualization object's animation is not played in "particle time". This is definately the wanted behavior, but isn't possible with the current state of dupliobject code.

Other new features:
- Particle systems can now be named separately from particle settings.
	* Default name for particle settings is now "ParticleSettings" instead of "PSys"
- Per particle system list of particle effector weights.
	* Enables different effection strengths for particles from different particle systems with without messing around with effector group setting.

Other code changes:
- KDTree now supports range search as it's needed for new boids.
- "Keyed particle targets" renamed as general "particle targets", as they're needed for boids too. (this might break some files saved with new keyed particles)

Bug fixes:
- Object & group visualizations didn't work.
- Interpolating pointcache didn't do rotation.

source/blender/editors/include/ED_physics.h

@@ -32,6 +32,7 @@
 
 /* operators */
 
+void ED_operatortypes_boids(void);
 void ED_operatortypes_pointcache(void);
 void ED_operatortypes_fluid(void);
 //void ED_keymap_pointcache(struct wmWindowManager *wm);