Merge pull request jquast#275

Closes jquast#273 by @grayjk,

> The following code enters an infinite loop:

    import blessed
    blessed.Terminal().wrap('\u5973', 1)

This PR fixes it by explicit check: when
- the given individual sequence is of length '2'
- and the wrap width is '1'
- and the cur_len is '0'

we cannot break down this "Wide" character any further -- so it is allowed to "flow outside" the given cell.

Bump version to 1.20.0

Bump version to 1.19.1

Fix metadata formatting (jquast#220)

Add 'Typing :: Typed' classifier

Follow-up on jquast#190, see https://pypi.org/classifiers/.

Cut version 1.18.0

bump for 1.17.12 release

Forgot to stamp 1.17.10, stamp 1.17.11

thanks to jquast#181, looks like I forgot to push a version
change commit before stamping, my master branch was 1
commit ahead, 1.17.10 was released to pypi, but the
code contents of github.com have read 1.17.9, this is
also bad for sphinx!

Anyway, we release 1.17.11 to avoid any discrepancies

Merge pull request jquast#178 from maybeetree/tmux_arrow_fix

Fix shift+arrow keys for tmux

Fixes and non-critical testing for Python 3.10-dev (jquast#177)