Merge pull request #960 from Nate-Devv/develop

Added partial support for DVORAK key layouts.
Items can contain components that differentiate them, even though they have the same stackId. They will stack together only, if the "equals" method on those components marked with @ItemDifferentiating returns true.
 Introduced an event for before inventory cell is rendered to allow drawing any background for items.
Removed OpenGLFont/HeadlessFont - no remaining implementation specific font handling.
Added in a liquid voxel shape + collision group for detection and interaction with liquids.
Merge branch 'develop' of git@github.com:MovingBlocks/Terasology.git into develop
Merge pull request #961 from MarcinSc/develop

Items can contain components that differentiate them, even though they h...
Restore hook for custom subsystem Font support
Merge pull request #963 from mkienenb/PR-Subsystem-font-hooks

Restore hook for custom subsystem Font support