UX improvements

[Kobzol]

• Show list of links to subclasses of a class
• Unify breadcrumbs (for modules) and add missing ones (for source code)
• Add source code links to specific lines
• Separate static methods to a different table
• Add expander icon (arrow) to classes in menu
• Remove standalone function pages, replace with links
• Add expander with complete doc comment to functions (together with link to source and import/override list)
• Improve UX of [imported] attributes (move them to a different place)
• Move docstring from init to the whole class (if class has no docstring)
• Improve keyword contrast and colors
• Reduce menu size (Javascript menu?)
• Parse reStructured text (links to classes and functions)