* fixed tukdag for new GLMain interface

* GLMain, GUI, DockGUI no longer use global handlers

* improvements to FIR

* cube rendering

* rasterize keyword works

* removed stages, added rangetype

* renamed image types

* changed `uvec` and `fvec` types to `vectype`

* `draw` supports viewport
* moved func argument for both `dispatch` and `draw`

* small change in dispatch syntax

* rewrote lowering

* typer can deduce stages

* fixed constant folding expression

support for `clear`

* low level support for rasterization

* initial support for constant expression folding

* scoped dump

* `sample` works correctly now

* range based form is beginning to work

* initial check-in FIR module