This results in less merge conflicts when using the
Text Editor > Files > Trim Trailing Whitespace editor setting.
.ptex, .mmg and .json files generated weren't modified
as these are saved by Material Maker. These files could be made
to end with a newline automatically on save in a future commit.
Added initial support for alpha channel (in combine, decompose and blend nodes). Textures with alpha channels can be exported using the material node albedo input.
Updated node editor with a simple editor for enumerated parameters.
