Client|Map Renderer: Added DrawList

Provides a drawable list of buffered GL primitives/or GL commands.
Client|Map Renderer: Added DrawLists

Encapsulates DrawList management.
Client: Added RenderSystem

Presently this merely acts as the owner of the DrawLists.
Client|Map Renderer: Began dismantling of the old render lists module
Refactor|Client|Map Renderer: Updated all drawing to use DrawLists
Refactor|Client|Map Renderer: Updated RL_RenderAllLists() to use DrawLists; cleanup

TODO: Redesign DrawList specification/"RTU map" stuff.
TODO: Revise plane geometry generation to build tristrips.
TODO: Replace the global map geometry buffer with GLBuffer(s).
TODO: Cleanup.
Client|Map Renderer: Cleanup
Refactor|Client|Map Renderer: Split NormalGeom into two separate groups
Refactor|Client|Map Renderer|DrawLists: Clear/reset draw lists and vertex buffer from RenderSystem

Also store a pointer to the vertex buffer internally within DrawList.
Refactor|Map Renderer: RenderSystem has ownership of the primary geometry buffer
Client|Map Renderer: Cleanup
Refactor|Client|Map Renderer: Relocated RL_RenderAllLists() to rend_main.cpp

There is no longer any real benefit in separating this from the rest
of the map renderer logic.
Refactor|Client: RenderSystem has ownership of renderer/renderer-appearance settings
Merge branch 'master' into gl2-drawlists
Client|Map Renderer: Began remodeling draw list specification/draw-state management
Client|Map Renderer: Continued remodeling draw list specification/draw-state management

Explicitly specify per-primitive GL draw state change properties at
DrawList::write() time, rather than copying them from the "RTU map".
Refactor|Client|Map Renderer: Removed the old "RTU map" mechanism

Now that we have an object-oriented interface to the draw lists this
sort of a mechanism is no longer useful.
Refactor|Client|GLTextureUnit|Map Renderer: Removed property GLTextureUnit::blendMode
Refactor|Client|Map Renderer: Began dismantling/remodeling GLTextureUnit

This component does not make sense in its current form.
Fixed|Client|Map Renderer: Rend_AttenuateLightLevel() returns values > 1.f

The rest of the map renderer expects [0..1] normalized light levels.