Added documentation for item trackers
Added link to source file on github for each page
Updated display of donation buttons
Adapted design so that vertical space at the top is better utilized
Reduced contrast in color scheme a bit
Added documentation for path handlers
Fixed headings capitalization, shell code and removed now unneeded h1 from top of pages
Replaced file with node where necessary
Added ref link def to content processors
Removed link_defs content processor from pipelines

This will not be needed anymore since we can now directly tell
kramdown predefined link definitions.
Moved templates for reference documentation to new location
Fixed links to API documentation pages
Added webgen API documentation via path_handler.api
Now using webgen's built-in facility for adding link definitions