If there's no `~/.shell.pre-oh-my-zsh`, don't assume the default choice
is Bash.  In fact Zsh is the default shell for macOS since Catalina
(10.15) [1], yet users of other OSes have likely to have Bash as their
default.

This commit fix issue #8252

[1] https://support.apple.com/en-us/HT208050

When ZSH_TMUX_UNICODE=true then tmux is informed that UTF-8 is supported.

Closes #5166

Fixes #8418

Fixes #8416

* Remove current directory from sys.path in python invocations

* Change project URL from robbyrussell to ohmyzsh org

* Update git remote to use ohmyzsh org repository

This prevents the jenv plugin from messing up the PATH and putting `user/local/bin` back at the front of the PATH, undoing any careful setup done before enabling this plugin.

Running `source ~/.zshrc` can have side effects, it's better to reload the whole 
zsh session with `exec zsh`.

Use add-zsh-hook to add functions to hooks. That way they won't be added again
when doing `source ~/.zshrc` multiple times.

Co-authored-by: Marc Cornellà <marc.cornella@live.com>

Also more quiet extraction. -D for cpio was not used due to additional
output.

Change `itunes` to `music`, as iTunes was renamed to Music in _**macOS** Catalina 10.15_

Co-authored-by: Marc Cornellà <marc.cornella@live.com>

Fixes #8368

* Update http to https in Solarized
* Upgrade http to https for 'Burger In Your Shell'
* Upgrade http to https for tmux.github.io

Piping stdin to emacs alias on MacOS was breaking (--tmpdir is not
supported in BSD flavored mktemp).

Tested in MacOS 10.14 and debian:buster to confirm it still works in
linux.

Closes #2214

$GIT_STATUS_IGNORE_SUBMODULES can be used to specify handling of
submodules. It can be:
not set : ignore dirty submodules (this was default zsh behavior)
"git"   : do not use "--ignore-submodules" and let git choose,
          this obeys setting in .gitmodules
other   : comes into "--ignore-submodules=$GIT_STATUS_IGNORE_SUBMODULES"

Fixes #8337

Never use `[[` for numeric comparisons, for that, we’ll use `((`.

Deleting `.mypy_cache` did not work, because the directories were not
empty.  They contain JSON files instead of compiled byte-code.

This extends the cleanup by also getting rid of `.pytest_cache`
directories.

* Add profiles documentation

* Fix order and reword some things

Co-authored-by: Marc Cornellà <marc.cornella@live.com>