The escape sequence (e.g. `^[[2 q`) was unsupported before and the
letter `q` was displayed as a typed character. The sequence is used by
Neovim for instance.
Now, it is properly parsed. However, it is ignored, so it won't change
the cursor style.
Because the escape sequence contains a space character, the
`gensequences` script had to be modified to support that. In the
`sequences` file, a space is represented as the string `SP`.
I initially committed libteken to sys/dev/syscons/teken, but now that
I'm working on a console driver myself, I noticed this was not a good
decision. Move it to sys/teken to make it easier for other drivers to
use a terminal emulator.
Also list teken.c in sys/conf/files, instead of listing it in all the
files.arch files separately.
