leftbar.html.yuidoc

- Simplified the render()/include() mechanism: I provide for some context-aware auto-completion of template specifics (name, format, theme). This avoids declaring template specifics redundantly. - For this purpose, renamed some of the templates to reflect their doc entity names: @object -> @object.html.asciidoc|yuidoc. - Theme-specific assets are now stored in a subdir of doc-assets/, named after the theme: doc-assets/yuidoc, doc-assets/asciidoc. - Adding the asciidoc assets subdir, including the asciidoc css - Renamed the theme "tmpl" to "yuidoc": This required to change the corresponding template extensions (*.tmpl -> *.yuidoc) and the include()/render() statements throughout the templates. - Removed the unneeded source.html.tmpl