bubo 0.11.0

This release adds voice: bubo can read corrections, practice answers and lesson
answers aloud with the voices already installed on Windows.

What's new

Listen to a correction: every correction card has a speaker button that
reads the corrected sentence.
Listen to the practice: after answering a card, hear the target answer
before moving on.
Listen to the lesson: the answer shown after an exercise can be played
aloud, including one-word blanks.
Built for learning: an installed English voice is preferred, markdown is
stripped so the voice never reads symbols, a new sentence replaces the previous
one instead of overlapping, and the button hides itself when the system has no
voices.
Practice fix: answering a card and pressing next no longer brings the same
card back. The session ends with "Tudo em dia" and extra practice is an
explicit choice.
Everything from 0.10.0: one concrete question per reply, safer data and
settings, safe deletion and backup, and the composer draft kept across modes.