Fix linking order of GLUI.
Update to GLUI 2.36.

Doesn't quite compile just yet.
Fix new warnings in new glui code.
Re-implement custom check_fit methods.
Add custom accessor methods.
Restore custom GLUI cursor functions.
Re-implement general mouse button handler.
Re-implement the rename and reposition methods.
Re-implement GLUI_StaticText::set_right_justify.
Re-implement GLUI_Checkbox::set_show_name.
Re-implement GLUI_EditText::get_event_key.

Seems a bit hackish though, but hopefully it works as intended.
Re-implement blocking windows.

There should be a simpler way to do this in GLUI... Somewhere at the
top-level instead?
Partly restore glui custom control classes.
Remove GLUI_Control->type from custom controls.
Fix GLUI_String usage in custom controls.
Fix RGB access in custom controls.
Fix custom control buffering functions.
Update drawing methods in custom controls.

It seems like this GLUI_DrawingSentinal (sic) handles checking whether
to draw and saving state. Hopefully this works correctly on the custom
controls.
Add OO construction API to custom controls.

There's not so much documentation on the newer GLUI's internals, so
hopefully I did this correctly.

Move custom control implementation out of header.
Use new OO construction API for GLUI everywhere.