Hud redesign

Included in this branch:
- Removed Blockly Button
- Refactored HUD & Ram related parts of `index.js`
- Removed the HUD's dependency on an active blockly node (fixed HUD disappearing in third-person)
- Removed unused events in `hudinstructions.js` (drag & drop, grid selection, etc.)
- Made inventory element display in-line to simplify it
- Smoothly decrease battery value while moving
- Removed ram HUD element (to be moved into blockly UI)
- Added new HUD images
- Tied rover and camera elements to new camera behaviors

Sorry for the nightmare pull request. Enjoy.
@eric79 @kadst43 @scottnc27603