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Add an alias for ```showpkg``` to get the reverse and recursive dependencies on a package

Fixes #3866

* use https everywhere

* use https links on the files that are left

Also, removed some broken links and updated redirections.

Added 'agli' to list all installed packages.
Added 'aglu' to list available updates only.

* Fix ubuntu ag alias clashing with the silver searcher

* Add aliases for git apply and git merge --abort

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Changing from `zcat` to `zgrep` because some `zcat` implementations do not work
if the file is not compressed.

Removing one "apt-get autoremove" alias because it is duplicated.

I use that command a lot of times, and there's no shortcut for that.
Now it does :)

Since #3902 lacks the auto-completion I made a PR for this as well.

Also fixes some typos.

* Easy to remember aliases
* Simplified
* Added aar() function for `sudo apt-add-repository xxxx && apt-get upgrade && apt-get install xxxx`