Bug 465701

I'd like to make some suggestions to improve the functionality of the annotations tools:

1. Separate color and tool selection
    For example sometimes i switch between highlighter and line but i then need to define both tool with every color which becomes a lot
2. Line behind text
     When OCR is not available or for equations the highlighter tool cannot be used so I would need to use the line tool. But the line is above the text and it would cover it, adding transparency to it both rends it a different color than the highlighted stuff and rends the content less readable. The highlighter tool fixes this by staying behind the content.
3. Box behind text
     To highlight an equation it can be useful to draw a box with highlighter mode. There's no other way to highlight equations otherwise since highlighter tools always gets the equations shape wrong.
4. Highlighter tool line thickness
     Adding the ability to change the highlighter tool line thickness. This means it's also fixed. I'd suggest a "Auto or value" type of selection.