UX improvements

[TodePond]

This PR makes some UX changes.

• The highlighter tool is placed earlier on in the toolbar (so that it's visible - not in the overflow menu).
• The live image tool is placed on the toolbar (so that it's visible - not in the overflow menu). Replaces the frame tool.
• The size style defaults to XL on load, as it works better with draw fast.
• The 'f' keyboard shortcut now selects the live image tool.
• The 'draw fast' button now creates a frame with no prompt.
• Frames with no prompt read 'double click prompt to edit'.
• Fixed not being able to click on the prompt input when editing.

[steveruizok]

Good changes! I'd put the frame left of the draw / highlighter tool. We could also consider creating a drawing tool that is better suited to this type of use, i.e. instead of using the highlighter colors / sandwich mode, just a big fat draw tool.

[steveruizok]

Either way for this PR I think it's good to go.

[TodePond]

Cool! Moved the frame (live image) tool left :)