Expanded to 4 models

Expanded to 4 models - Standard, standard 3D printer, Plus, Deluxe. These models are based on maker suggestions.

USB DAC, speakers

• Formalized support for StarTech/Syba USB DAC, in addition to the Pi's built-in headphone jack.
• Switched to pmount for USB drive auto mounting.

Bamboo case + Raspberry Pi A+

v4.01

No real changes, just housekeeping prior to releasing v4.01