Support the Black Speech case of General Use mode

Support the Black Speech case of General Use mode

-   Add support for black speech option for general mode, which reverses curls,
    uses extended tengwa for "sh" and "gh", and uses ore before consonants in
    addition to final position.
-   Add extended forms for ando, umbar, anga, and ungwe.

Also

-   Fix a minor bug in Classical mode for distinguishing final position before
    punctuation.
-   Generalize column code to detect whether a tehta can be placed above or
    below after the tengwa is reversed.
-   Share common column builder code between Classical and General Use mode.