#180 Client Side Action Plugin

[Robert MacGrogan]

Allow users to customize/configure action plugins.
Action plugins will display as menu items. Must somehow
be able to configure enable/disable on file selection,
project selection, etc.

Action plugins can display dialogs and fire server-side
action plugins.

Must also come up with a way that plugins can modify
screen layout so that a flat (no tree view) file
listing is used.