Fix key-down+key-up mis-ordering when both occur in the same frame.
Fix sub-frame input handling.

This needs IN_Frame() to be called often, maybe more than once per frame.
Timestamps reflect when this was called rather than the actual event times,
so we work around this by calling it from within the delay loop in
Com_Frame(). Wake-up within that loop is approx. every 50ms, so the
minimum calling frequency should be 20Hz.
Removed unused vertex/triangle optimization code

When enabled, the renderer won't compile.
When this is fixed, map load times are increased dramatically without any improvement to runtime performance and very little difference to vertex/index counts.
Remove unused shader "models/buildables/drill/energy".
Add back a commented version of "models/buildables/drill/energy" since it's used by the low poly drill model.
Cleanup a cast inside generic_vp.glsl.
Only download dependencies if NaCl is in use.

Downloading at package build time is Not Allowed. This is a compromise.
Merge branch 'master' into nacl