# Use delegate

There is a common pattern in the editor plugins where we allow
other plugins to take over the handling of a command. In order to
make it explicit in the code, this commit introduces a new utility
function called delegate that will be used to call the handlers.


# Use trigger

In the editor, the pattern to dispatch events from one plugin to other
plugins is to use the resource mechanism that aggregates callbacks to
a specific resource. In order to make it clear when reading code that
we want to dispatch an event, this commit introduces the util function
trigger that communicates the intent to the reader.

# Remove dispatch

Reasons:

1) It is a redundant mechanism, we can achieve the same result though the use
of shared and resources.
2) Using the shared or the resources is more explicit. If we need to call a
command from a specific plugin, we should depend on the plugin and use the
shared. If we need multiple plugins to react to an "event", we should use the
resources.
3) We should distinguish between a "user command" and a "system command" or
"system event".
- A "user command" is anything that a user could configure as a shortcut,
toolbar item, powerbox item, or power button.
- A "system command" is a shared method.
- A "system event" is a resource.
4) When debugging, it was harder to "step into" a dispatched command as we would
step into the `handleCommand` of every plugins.

For `toolbarItems` and `powerboxItems` now inherit the properties of a user command
through the `commandId` property (if specified).

The power buttons now use the definition of the user commands instead of the
powerbox items.

The `toolbarItem` `Component` does not includes dispatch in the props by default
anymore, we need to specify the callbacks in the props of the `toolbarItem`
explicitly.