glslwatch provides a live glsl source with include support.
Construct the GLSL source tree by passing the shader path and a vec of paths to search for included files.
let include_dirs: = vec!;
let src_tree = new?;
The fully rendered tree is cached in memory and we can retrieve it with
.render().
let src_str = src_tree.render;
We can refresh the tree if it is expired.
let src_tree = if src_tree.expired? else ;