Removed stm32_can and usps_f407 platforms.
Fix build for f4discovery host.
Add a version of BMP-mini optimized for manual production

This commit adds a variant of the Blackmagic Mini that uses only 0603
parts and standard connectors for better availability and easier manual
soldering.

Additionally, another voltage regulator has been used that is
cheaper, pin-compatible and has better characteristics.
Moved entropia design to contrib directory and added description.
Updated project README.
Modified BMP Mini with extra connectors