UI tweaks

[brickbots]

• Rename 'Preview' to 'Camera'
• Add 'Camera' to main screen rotation (just 'A')
• Add option to adjust amount of BG sub in 'Camera' with default at 50%
  • This is mainly to make it clear that this is different than Chart and that it's showing a live view
  • Also avoids the completely black overexposed situation
• Change 'B' button on catalog to switch between description / image
• Add ** Logged x times at bottom of object descriptions
• Function button hints, with customizable timeout