More Latin Extended-B

1. Changed b-with-topbar (uni0183) to have the normal top serif of b
(like in Gentium)

2. Adjusted top serif of small letter tone six (uni0185) to have same
underside curve as top serif of b

3. Redesigned open O, to look less like a flipped C and more like a
broken O. (Warning: *very* non-canonical shape!)

4. Thickened hook on c-with-hook

5. Replaced ball terminal on captial letter V with hook (uni01B2) with
top serif of open O.

6. Shortened "inverted glottal stop with stroke" (uni01BE) to be the
same height as t; adjusted bearings

7. Remodelled hooks on Z-with-hook and z-with-hook (uni0224 and
uni0225) on cedilla, for better consistency

8. Adjusted bearings of uni01F0, uni0236, uni0237 and uni0238.

9. Remodelled "hoods" of capital and small letter glottal stop (uni0241
and uni0242) on those of capital and small yogh (uni021C and uni021D)

10. Added uni0238 and uni0239 (the db and qp ligatures) to the {a æ …}
class, which includes d and q.
Open O

Remodelled lower part of open O using the tail of IPA g (uni0261). Why
didn't I think of that before?
Glottal stops, spacing around slashed letters

Remodeled the "hoods" of capital and lowercase glottal stops (U+0241
and U+0242) on the basis of uppercase and lowercase Yogh.

Also, adjusted bearings of vaious slashed(/hooked) letters (023A–023E,
0243–024F), and added some of these to the appropriate kerning classes.
That does it for Latin Extended-B, I think.