Only display dates and author if the included page exists
Add the id to the p_cached_instructions-call

This makes the page id available in the cache handler event.
Fix and clean up of initial definitions and includes
Change editx support into pagemove support (both experimental)

I decided to focus on the old pagemove plugin instead of editx, my
pagemove fork contains a lot more fixes than my editx fork. This changes
the include plugin to support the pagemove plugin instead of editx.
Adjust internal links to be local if the target page is included

This changes internal links in included pages whose target page is
included into links to the target page. This only works for xhtml output
with additional support for the dw2pdf plugin, other output formats are
not affected by this change.