QUnicodeTables: some internal API renamings

QUnicodeTables: some internal API renamings

enums GraphemeBreak, WordBreak, and SentenceBreak has been renamed to
GraphemeBreakClass, WordBreakClass, and SentenceBreakClass respectively,
their values has been renamed to contain a '_' as logical enum-value separator
(just like many other nums in Qt, e.g. LineBreakClass);
*BreakFormat has been replaced with *Break_Extend (some format characters are
kind of subtype of the extender characters, not vice versa).

Change-Id: I9ddbcf8848da87409736c2d6d1798a62fa28cab8
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>