Start system populator framework.

Adds buoys, nothing else
Fix typo making a random seed function non-deterministic
Make sure new populator runs on all branches, replicate (ish) old populator behaviour.
Add last named location that doesn't need high-precision space
Upgrade world-space coordinate vectors to double-precision (issue #22)

Introduces several bugs, probably.
Start adjusting camera setup to make use of high-precision space

Several more entity types still need to set up cameraRelativePosition on init.
Space dust doesn't work yet.
Fix space dust, particles, demo ships
Fix exhaust plume display.

Display and game engine seems spatially stable out to 10^14 units from the origin (~0.01 LY, or thereabouts) which should be enough for any sensible purposes.
Make Javascript vector conversion high-precision where necessary
Fix collision detection at HP ranges
Re-enable frustum culling, fix display of planet atmosphere and flashers
Finish populator named locations (issue #36)
Add system repopulator

Runs every 20 seconds to keep number of ships in system up
Nova system population

Changes default populator for system, for easiest compatibility with old save games, OXPs with novas, etc.
Make navigation buoys rotate again
Make system.populatorSettings work, cleanup and document
Fix under-retention (related to 5636606)
Correct variable name in script
Fix harmless compiler warning in Octree
Merge branch 'master' of github.com:OoliteProject/oolite into javascript-populator

Conflicts:
	src/Core/Entities/ShipEntityAI.m