TidlyWiki conversion: proc-layer tiddlywiki

[ichthyo]

Extract the content of the Proc-Layer TiddlyWiki (renderengine.html) and convert it into a tree of asciidoc pages, maintaining proper links, table formatting and inclusion of images.

[ichthyo]

Personally, I'd propose to leave this TiddlyWiki as it is for now and wait until uWiki is usable and the new organisation structure of the documentation is generally set. Because the content here is really crucial for the further development, and a broken state or even not being able to maintain it as easily as in the TiddlyWiki would be problematic. Anyhow, on the long run, all documentation should be united in a GIT repository accessible through uWiki.