Tech/LxEngine/Samples/LxQuake2

Cvar
Quake 2 has a Cvar system that has commands and properties. These should become properties and methods on the Engine and Document (and Element, by extension) respectively. Q2 does not explicitly give them a scope like that, but LxEngine should.

Cvars have flags. Currently lxvar handles property sets and lxvars do not have flags. Should optional flags be added?