Update Oh My Fish and packages.

== USAGE
  omf update [<package1> [<package2> [...]]]

== DESCRIPTION
Updates Oh My Fish, package repositories, and installed packages.

Each package name that is given will be updated. For example, to update the packages `bobthefish` and `direnv`, run:

  omf update bobthefish direnv

The special package name `omf` will cause Oh My Fish to update itself. This can be combined with other package names.

If no arguments are given, all installed packages will be updated along with Oh My Fish.

== ALIASES
*omf u*, *omf up*
