Some work on contextual Latin ligatures

Breaking ligatures into individual components, not finished nor used
yet.
Allow initializing tests with positions
Run the positioning tests with the regular font

… for now, I need to redo the whole test suite to be more fine tuned.
Add test for the small alef hack
Some adjustments to the documentation
An ugly hack for the missing U+0671 in DejaVu Mono
Minor doc fixes
Change section tiltle font and spacing
Put a gray background behind code point numbers
Change text and background colors
Remove old HTML documentation
Minor