fix #241
Helped-by: Yogesh Dhamija <ydhamija96@gmail.com>

Problem:
dirvish#add_icon_fn() may truncate filenames from the left, when icons
are being applied.

To see the issue, create files 'abc-file.txt', 'defg-file.txt', and
'file.txt' in a directory and display them in a dirvish buffer.  All
filenames display as 'file.txt'.

The problem seems to occur when the basename of one of the files in the
directory matches the right-hand portion of one or more other filenames
in the same directory.  However, experimentation shows that it does not
always happen in this case.

Solution:
Define each pattern to match an exact line.

Essentially reverts cfc66aa.

- `q` is much more ergonomic than `gq`.
- `q` continues to win in the wild, and is used for e.g. quitting
  a `:Man` buffer.
- "quit" is a vastly more-common use-case than "record a macro".
- One can use a mapping like `\q` to opt-in to macro recording when it
  is needed.

Problem:
`{Visual}O` and similar commands only operate on a single file
since 6233243 #235.

Solution:
Use `line('v')` and `line('.')` to get the visual range when
the `<Cmd>` mappings are used.

Problem:
If "." is used on a file with "%" or "#", Vim treats those as special
chars.

Solution:
Pass the {special} arg to shellescape().

Closes #145
Closes #253