Add UIComponent code for iframes
Create a script for connecting UIComponent iframes with their parents
Fix tests for UIComponent
Add an example test for UIComponent
IFrame framework; develop demo.
Close UIComponent iframes when pressing esc by default
Initialise hide/show styles for UIComponent
Small changes to UIComponent
Allow message passing directly from UIComponent.show
Update test for UIComponent
Remove key handling in UIComponentServer/UIComponent code
Update UIComponent test
Add UIComponent.active, so we can specify whether to focus the frame
Update UIComponent test
Refactor UIComponent, etc., and demo.

- Simplify component API.
- Iframe flashes on re-focus.
- Probably some other stuff which I've forgotten.
Clearer handling of @showing in UI component.
Merge branch 'smblott-uicomponent-iframe' into post-1.46-with-uicomponent-iframe

Conflicts:
	content_scripts/vimium_frontend.coffee
	manifest.json
Remove UI component demo.