- Define a collection of legal characters when parsing page and section
in `s:parse_page_and_section()` instead of relying on 'iskeyword',
which is unreliable.
- Allow non-numeric section names (e.g., `3c`).
- Simplify argument handling in `man#get_page()` to accommodate
non-numeric section names.
Fixes#4165.
- do not create leader maps
- :norm! instead of :norm
- :keepjumps during layout
- use blackhole reg to avoid polluting unnamed reg
- format buffer name as "man://foo(2)"
- simulate behavior of `man`
- buffer-local mapping of q to quit
- open in new tab instead of new window
- set 'nolist'
- set tabstop=8