Paul, just a minor note about a particular pdf function argument. (pertaining to the text alignment)
Know that 'centre' (GB) and 'center' (US) are both covered by the pdf class. [see includes/class.pdf.php, lines 105 and 107]
So even though there appears to be a minor misspelling with 'centre', that is actually intentional.
As you cross other PDF-generating files, MANY instances of 'centre' will be found, as well as other possible mixed use.
I used to think that this was an issue myself when I first started with weberp, so you would not be the first. I'll keep your change since it is covered both ways.
Changes committed
to SVN.