* Add virtualfish plugin to the registry

Fix double key bindings load

Fixed spelling error

makes package docs better by refreshing hooks documentation
and also contributing process.

When I upgraded my omf peco stopped to work I had to change the repo to this one that seems the one the is currently maintainable.

* init: load only key bindings from current theme

* theme: reload key bindings on theme change

Refactor autoload: Split the big function into two smaller ones,
doing only option parsing at main function.

The algorithm is also rewritten, now in two steps for both path
inclusion an exclusion functions: 1) use auxiliary lists to store
valid function and completion paths, 2) bulk insert or remove just
once in the variable.

Now also respects path insertion policy, keeping user function
path always in front of other paths, thus allowing precedence of
user functions.

* init: rewrite init process

Now use pure globbing to generate 100% valid function and
completion paths, effectively splitting the init process in two
steps, one which paths are added, and other when initialization
is done (sourcing init).

This initialization code introduces a new interface for
`init.fish` hook, which deprecates the previously used event
model. The new interface injects three variables into `init.fish`:
path, package and bundle. This variables can be used by the
package to autoload paths, use bundled files, etc.

Also supports key bindings by sourcing
$OMF_CONFIG/key_bindings.fish and also key_bindings.fish in
packages (plugins and themes) root directories. This is done
when fish_user_key_bindings is called.

* omf: migrate to new init hook

* omf/templates: migrate to new init and uninstall hooks

* docs: document new init and uninstall hooks interface

* README: update new hook interface spec

* update version constant to 2

Add wttr plugin to omf

Add a wttr plugin to omf that interfaces with wttr.in service and shows weather information

Add new search command

Describe all packages fixed