FEATURE REQUEST:
Make the Sketchbook menu a first level menu.

RATIONALE:

1. The Sketchbook is used very often in the IDE and it's quite fiddly to
access it continually. It is very frustrating. To access it you have ot do
the following:
- Move mouse to file Menu
- Click it
- Move mouse down.
- Move mouse accross to skethbook
- Then the contents are revealed.
If the Sketchbook was a top level menu the actions would be this:
- Find & Click Sketchbook Menu
- See contents.
For something that is accessed so regularly, that's quite a saving of time,
mouse movement and hassle. For windows users, it would also make keyboard
navigation of the sketchbook much more accessible.

2. The sketchbook is a concept in Processing that is not found in a lot of
other tools. People will often be coming from things like Photoshop or Word
where you handle all of your files. Using the Sketchbook is a different
mental model that I have seen confuse many beginners. Having the Sketchbook
would reinforce this idea, and help people get a better understanding of it
right from the start.

I think there would be a great benefit in upgrading the Sketchbook to it's
own menu item, so do consider it.

Rather than adding a new menu, why not click the open button in the
toolbar, which pops up the sketchbook menu?