Smaller tables (#68)

Smaller tables (#68)

* convert sequences to utf-16 (saves 25kb)

* store sequence length in properties instead using -1 termination (saves 10kb)

* cache index for slightly faster data creation

* store lower/upper/title mapping in sequence array (saves 25kb). Add utf8proc_totitle, as title_mapping cannot be used to get the title codepoint anymore. Rename xxx_mapping to xxx_seqindex, so programs assuming a value with the old meaning fail at compile time

* change combination array data type to uint16 (saves 40kb)

* merge 1st and 2nd comb index (saves 50kb)

* kill empty prefix/suffix in combination array (saves 50kb)

* there was no need to have a separate combination start array, it can be merged in a single array

* some fixes

* mark the table as const again

* and regen