Split compound.* into multiple files by domain

By relocating according classes into compound_registry.*, compound_absorber_system.* and compound_emitter_system.*, issue #116 should be resolved.

- CompoundMovementSystem was kept in compound.*, because it is directly and only(*) linked to the CompoundComponent.
(*in relation to everything else that was located in compound.*)
Merge pull request #201 from HariboTer/issue-116

Split compound.* into multiple files by domain
Fixed issues with keys not always being consistent for GUI/game key consumption
Merge pull request #194 from Revolutionary-Games/183-key-events

Key problems with gui fixed.
Increased the max hex value to prevent crashing when fully zoomed out and placing organelles.
"Fixed" minor style deviation
Merge pull request #210 from HariboTer/207-Undo-redo-feature

Implemented undo/redo-feature for MicrobeEditor
A simple sliding-window 2D array datastructure, designed for cheap movement of the window of active elements.
Exposes the following to Lua:
 - constructor(width, height, resolution)
 - ::move(dx, dy)
 - ::get(x, y)
 - ::set(x, y, val)
Notes:
 - Currently not generic, but that should be easy once it's necessary
 - All x/y/dx/dy values are given in terms of the world coordinate space
 - Indexing locations outside of the current window area gives you the default value, and any input ot such a spot is ignored.

See #165
Merge pull request #193 from Revolutionary-Games/165-rolling-grid

A simple sliding-window 2D array datastructure, designed for cheap movement of the window of active elements.
Made a simple .travis.yml that does nothing and exits successfully.
see #214
Merge pull request #215 from Revolutionary-Games/214-NOP-travis-yml

Created a nop .travis.yml, that does nothing except exit successfully. Gets rid of clutter until we can put together a build that runs on the travis machines.
Added pausing to the game during menus.
Merge pull request #220 from Revolutionary-Games/150-pausing

Added pausing to the game during menus.
Added a hex grid to the microbe editor. Can be toggled with 'g'
Merge pull request #208 from Revolutionary-Games/202-editor-grid

Added a hex grid to the microbe editor. Can be toggled with 'g'
Added a series of useful console commands for debugging and cheating.
Merge pull request #205 from Revolutionary-Games/188-console-commands

Added some basic console commands.
Fixed some issues with 3D sound. Added sound effects for microbe movement, death, collision and more.
Merge pull request #219 from Revolutionary-Games/119-sound-effects

Fixed some issues with 3D sound. Added sound effects for microbe movement, death, collision and more.
Added a new "toggleGuiMove()" console command, to enable users to finely adjust gui elements with right click and get positional data to use in layout files.