scripts and paired chars revisited

[Matthias Clasen <mclasen redhat com>]

I have attached another version of the easy-scripts-and-paired-chars
patch to http://bugzilla.gnome.org/show_bug.cgi?id=320666

It improves upon Federicos latest version in the following ways:

- make pango_script_for_unichar a simple wrapper around
  pango_script_for_unichar_with_last_index()

- remove ranges below 0x2000 from pango-script-table.h

- make better use of the information contained in last_index
  by using failed tests to reduce the range for binary search

- use the fact that all paired characters are Common to avoid
  more get_pair_index() calls


Maybe somebody wants to measure this version ? I haven't
tested it beyond compiling it...

Matthias