UI: Optimize ship particle effects

Add particle meshes to position / location trackers so that they
don't need to be manually updated in event handlers
UI: slight reorg of star & station modules

Includes a fix to base particles handling edge case
where num_emitters = 0, no functional changes beyond this.
UI: remove some unused modules, simplify a few classes to mixins
UI: update scripts included in test runner, split up test setup
UI: split js location into modular mixins / include in main class
UI: entity refactoring & test fixes

Rounds out JS entity refactoring w/ asteroid, galaxy, jump gate,
and planet classes / modules.

Also includes a few small fixes + utilty improvement to central
ui and page modules.

Finally includes many fixes to ui test suite including the
incorporation of new site layout / modules and fixes to the
galaxy, jump gate, planet, solar system, and other tests