Improved shader editor

[c42f]

• Less sucky indentation
• Basic emacs-like line editing shortcuts
• Syntax highlighting

This is too much work to do from scratch, but might be plausible if a text editor widget can be taken from another Qt project.

[c42f]

Here's a possibly superior alternative: Improve the socket interface so that it's easy to grab the current shader and save it back via the socket or a watched temporary file. This would make editing the shader from <your favourite editor> possible.