* a simple 'demo' grade 2 encoder table. It's pretty dumb, but
does unconditional string substitution of all the contractions.
* Fixes for offset math - the offsets reported are now correct,
and they get properly reallocated if the input or output strings are really
big.
* Added BrailleConsole API, which is convenient for an all-in-one
encoder/driver object used by clients.
* Refactored the BrailleTableEncoder implementation, created new header
braille-table.h.
* More control of encoder behavior by means of 'flags' on the output buffer.
Implemented support for context changes when tables delegate, which allows
support for things like the ICEB recommended context-switch dot patterns.
