Merge pull request #47 from samwilson/upgrade-mpdf

Upgrading mPDF to latest version (5.6).
Merge branch 'master' of https://github.com/splitbrain/dokuwiki-plugin-dw2pdf
Add support for embedding non-standard fonts (i.e. any on the system) in generated PDFS.

This follows the same configuration as mPDF's config_fonts.php file; see http://mpdf1.com/manual/index.php?tid=453 for information.

Templates can add a config_fonts.php file, that defines a single $fontdata array (i.e. doesn't return it, and it's not $this->fontdata as mPDF has it, but just $fontdata = array(...);).
Merge branch 'custom-fonts' into samwilson