Various bugfixes
louis:translate-file: add @pages attribute with page count
Make parsing-helper.xsl more powerful

* possible to have multiple rulesets in the inline stylesheet (e.g. {...} @page {...} ::before {...})
* put regex helper functions in separate file
* did some renaming too
louis:translate-file: prefix page-layout options with louis:
Move validate-braille to utilities and use in louis:format
braillecss: support counter-reset
louis:translate-file: add 'louis:braille-page-begin' parameter
Include @page {...}, ::before {...} and ::after {...} in CSS @style attribute

* css:inline replaces css:apply-stylesheet
  - doesn't have a page-layout output port anymore
  - doesn't insert css:before and css:after elements anymore
  - puts everything in the @style attribute instead
* block-translator-template becomes responsible for translating ::before and ::after pseudo-elements
* louis:format now has to do more CSS parsing
  - extract page-layout info from inline CSS
  - extract ::before and ::after content
louis:format: page numbering improvements

- support counter-reset: braille-page ...
- make sure page numbering is still correct when document is split in multiple sections
fixup 9787a2ed7366069d
louis:format: proper whitespace handling
Refactoring

* Divide modules into low-level ('utils') and high-level ('scripts')
* Renamed some modules, added some new modules
* Each group (css/pef/liblouis/...) now has a respective utils module that
  acts as a facade for other modules. It collects all XSLT functions / XProc steps
  into a single library.xsl / library.xpl to make importing easier. Some
  XSLT libraries are just 'dummy' libraries that can be imported to make it
  clear that certain Saxon XPath extension functions are used.
Fix for add-metadata
load-translator: better error messages
Make validate-braille more like p:validate-with-*
Don't create temp dir in xml-to-pef.convert

Creating (and deleting) directory becomes responsibility of
caller (zedai-to-pef or dtbook-to-pef)
split-into-sections bugfix

For each section, copy over last occurences of `louis:print-page`,
`louis:running-header` and `louis:running-footer` from preceding
sections.
Add pef:validate (untested)
Update to latest version of jStyleParser (1.13)