There are a couple of minor nuances with parsing script values, compared
to other properties. In Scripts.txt, the UCD file lists the full name of
each script; other properties, like General Category, list the shorter
name in their primary files. This means that the aliases listed in
PropertyValueAliases.txt are reversed for script values.
This downloads the PropertyValueAliases.txt UCD file, which contains a
set of General Category aliases.
This changes the General Category enumeration to now be generated as a
bitmask. This is to easily allow General Category unions. For example,
the LC (Cased_Letter) category is the union of the Ll, Lu, and Lt
categories.
Adds methods to retrieve a Unicode property from a string and to check
if a code point matches a Unicode property.
Also adds a <LibUnicode/Forward.h> header.
