* updated transform node (scale split into scale_x and scale_y, and added a repeat parameter)
* added blend modes (burn, dodge, lighten and darken)
* added a (very bad) blur node, based on generic convolution code
* rewrote normal_map node using convolution code
- 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
Added Image node that can be used to import textures
Renamed all get_shader_code methods to _get_shader code so a caching system can be integrated in node_base (and we can get rid of get_source_rgb and get_source_f functions)