Adding a new experimental installer script
Fix init and add completion (but commented out)
Fix root for zsh
try to fix for zsh again
Make sure we have an absolute path.
Update docs for new installer
s/type -f/type -t/ to check for __gitcomp function

In `lib/git-hub.d/init`, to check for the availability of a `__gitcomp`
Bash function, use `type -t __gitcomp` rather than `type -f __gitcomp`.

From my limited testing, `type -t` appears to give the desired output,
whereas `type -f` would not.
Load Bash compl even if `__gitcomp` already exists

In `lib/git-hub.d/init`, load the Bash completion facilities for `git
hub` regardless of whether the `__gitcomp` Bash function, defined by the
standard Git completion script, was already available without
`lib/git-hub.d/init` needing to source the standard Git completion
script.

Previously, the Bash completion facilities for `git hub` would only be
loaded if `__gitcomp` was not available prior to `lib/git-hub.d/init`’s
execution, which did not seem to me to be the desired behavior.
`lib/git-hub.d/init`: Load Bash compl only in Bash

In `lib/git-hub.d/init`, load the Bash completion facilities for `git
hub` (and for `git`) only if running under Bash (a status which is
assumed to be true if the shell parameter `BASH_VERSION` is non-null).

(Note: the diff is mostly increased indentation; it might look
friendlier with `--ignore-space-change` (`-b`).)
Add basic zsh completion script

Add a basic zsh completion script for `git-hub` and `git hub`, at
`share/zsh-completion/_git-hub`, that, if hooked into the zsh completion
system, simply causes zsh to complete available `git-hub` subcommands
(as listed in `lib/git-hub.d/completion`).
`lib/git-hub.d/init`: Set up zsh compl when in zsh

In `lib/git-hub.d/init`, when executing under zsh, prepend the path
`$GIT_HUB_ROOT/share/zsh-completion` to the zsh array parameter `fpath`, so
that our zsh completion script, which is in `share/zsh-completion`, will be
hooked into the zsh completion system.
init: Search more thoroughly for Git compl script

Previously, in `lib/git-hub.d/init`, when executing under Bash, the
standard Git completion script for Bash was checked for only at the
file-path `/etc/bash_completion.d/git`.

None of my computing devices (whether they run Gentoo Linux, Ubuntu
Linux, Mac OS X (with MacPorts), or — going on an assumption here —
Android) have a `/etc/bash_completion.d/git` file; however, Ingy döt
Net’s Ubuntu system reportedly does have such a file.

Having found, in a Git completion script for zsh (that’s in Git’s
repository, but is different from the standard Git completion script for
zsh that’s in zsh’s repository), a list of file-paths whereat the
standard Git completion script for Bash might be found [1], and also
having found the location of the standard Git completion script for Bash
on my Gentoo, Ubuntu, and Mac systems —

 - `/usr/share/bash-completion/git` (Gentoo),
 - `/usr/share/bash-completion/completions/git` (Ubuntu),
 - `/opt/local/share/bash-completion/completions/git` (MacPorts)

— I’ve extended the section of `lib/git-hub.d/init` concerned with
finding and loading, if necessary, the standard Git completion script
for Bash such that it should check for that script at all the above
file-paths.

[1]: <https://github.com/git/git/blob/4109c28e055dba27d73cefb956bea5e611f66ec0/contrib/completion/git-completion.zsh#L34-L36>
Move `init` script to top level and update docs
mv lib/git-hub.d/completion share/completion.bash

Move `lib/git-hub.d/completion` to `share/completion.bash`, at Ingy döt
Net’s request, and update references in source files to that file
accordingly.
`lib/git-hub.d/init` → `init` in zsh compl file

In the zsh completion script, `share/zsh-completion/_git-hub`, update a
reference to `lib/git-hub.d/init`, which was moved to repository
top-level, to refer instead to that file’s new location.
Fix misplaced–grave-accent typo in zsh compl file

In the zsh completion script, `share/zsh-completion/_git-hub`, I had
misplaced a U+0060 GRAVE ACCENT, inside a string literal.

This commit fixes this typo.
Fix missing–grave-accent typo in `git-hub.swim`

In the Swim documentation document, `doc/git-hub.swim`, the closing
U+0060 GRAVE ACCENT of an inline code span had been omitted.

This commit fixes this typo.
Quote whole example manually-set (MAN)PATH values

In the Swim documentation document, `doc/git-hub.swim`, an example of
setting one’s `PATH` and `MANPATH` environment variables, so as to
include git-hub’s `lib` and `man` directories, manually (as opposed to
via the `init` script) showed only parts of the example values quoted,
which parts did not include the added elements, i.e., the paths to
git-hub’s `lib` and `man` directories.

These added paths may contain characters requiring quoting, so this
commit changes this example to instead have the whole values be quoted.
Expand `doc/git-hub.swim` § Command Completion

In the Swim documentation document for `git-hub`, `doc/git-hub.swim`,
expand the Command Completion section, in particular, to cover:

 - the generally preferable option of using the `init` script rather
   than enabling completion manually;
 - zsh as well as Bash; and
 - the various file-paths whereat the standard Git completion script for
   Bash might be found.
mv lib/git-hub.d/git-completion share/git-completion.bash

Move `lib/git-hub.d/git-completion` to `share/git-completion.bash`, at
Ingy döt Net’s request, and update references in source files to that
file accordingly.