Bugfix for odd/even table head

When the table starts on a page where there is
not enough room for the table head, we move to the
next page. But for the logic of the table, we
are still on the first page. tablepart_absolute
reflects this and is increased only if there is
a real table page break.
New experimental XPath implementation
Move xpath functions to the xpath parser
    
Having the xpath functions in the parser file
makes testing much easier.
XPath: bugfix
XPath: Fix value temporarily
Merge branch 'xpath-experimental' of github.com:speedata/publisher into xpath-experimental