search for: uff00

I think I found a bug in Xapian 1.5 when using FLAG_WORD_BREAKS for input that contains characters in Unicode Halfwidth and Fullwidth Forms (https://unicode.org/charts/PDF/UFF00.pdf). Since I am undecided yet if and how to fix this in Xapian I haven't come up with a pull request. Because trac currently is offline, I could not file a bug. I hope it's OK to post my analysis here first, I'll be happy to follow up reporting that bug proper later (should we conclud...