The end condition in the binary search loop in the new getType() was

incorrect. I must have written that binary search idiom a hundred
times, so it's rather embarrassing that I can't _automatically_ get
it right! This was causing all kinds of characters to be classified
as ON when they should have been various other classes.

Also while I'm here, I've added another test case to utf8.txt (a
small piece of Arabic within a predominantly L->R line), and also
supplied a means to compile minibidi.c with -DTEST_GETTYPE to
produce a command-line character class lookup tool. (Not sure what
use that'll be _other_ than debugging this precise problem, but I
don't like to throw it away now I've written it :-)

git-svn-id: svn://svn.tartarus.org/sgt/putty@5016 cda61777-01e9-0310-a592-d414129be87e