`.import` files (not to be confused with the `.import/` directory)
should be included in version control as they contain important
metadata, such as whether a texture should be filtered or not.
A `.gdignore` file was added to the `doc/` folder of the add-on,
which prevents Godot from importing any files inside.
This also speeds up the initial editor import step.
Refactored rendering of textures for save and exporting material now saves all textures.
Added an option to start a clear the project, and proper "save" and "save as..." options.
Added support for disconnects.
- shader updates are delayed by .25 seconds to avouid UI freeze
- fixed GraphNode initialization upon loading
- started obsoleting get_source_rgb and get_source_f functions
- updated colorize node to use gradient
- image node can now be loaded/saved
- removed iqnoise node
- rewrote perlin shader to support a seed parameter (seed is calculated from the node's position, so just move it to reseed)
- Added voronoi noise node
- updated code to use % formats instead of concatenating strings (should solve type problems in shaders)
- reworked the context menu (now has submenus)
- fixes in the gradient editor
