Started branch for resource system refactoring

The goal of the 'resourcesystem' branch is to establish a framework
for all resource system components including Materials and Textures.

Primarily this work will consist of introducing a RenderSystem, which
is derived from de::Subsystem and then relocating existing management
systems here.
Added: ResourceSystem (stub)
Refactor|Client|Server: Initialize ResourceSystem; take ownership of de::Textures
Merge remote-tracking branch 'remotes/origin/master' into resourcesystem
Refactor|Client|Server: ResourceSystem has ownership of ResourceClasses
Refactor|Client|Server: Relocated most of r_data.cpp into ResourceSystem
Refactor|Fonts|Resources: Minor Fonts collection cleanup
Refactor|ResourceSystem|Client|Server: ResourceSystem has ownership of the Fonts collection
Refactor|Fonts|Resources: Began overhauling the Fonts resource collection

Note that it does not build yet. Still lots more work to do...
Refactor|Fonts|Resources: Continued overhauling the Fonts resource collection

Now builds and links. Printing/querying of font resources from the
console is presently disabled (todo).
Refactor|Server|ResourceSystem: The server does not need a Fonts collection

The collection is no longer initialized and no logical Font resources
are instantiated on server side (Font definitions are parsed, but not
processed into resources).
Refactor|ResourceSystem|Fonts|Client: Cleanup of Font resource management continues
Refactor|Fonts|Client: Began cleanup of (composite) bitmap fonts

Obviously the ultimate goal here is a representation which can be
integrated with/on-top-of de::Font in libgui. I won't be taking it
quite that far at this stage, however.
Refactor|Fonts|Client: Completed initial C++ translation of (composite) bitmap fonts

Todo: Cleanup.
Refactor|Fonts|Client: Relocated font components to new source files
Refactor|Fonts|Client: Added convenience headers for font components
Refactor|Fonts|Client: Renamed font components following deng naming conventions
Refactor|BitmapFont|Client: Applied pimpl idiom; cleanup
Refactor|CompositeBitmapFont|Client: Applied pimpl idiom; cleanup
Refactor|AbstractFont|Resources|Client: Removed obsolete fonttype_t