Enable Wconversion for Linux for CI to be used as regression. Fix esc_hw.c warnings by adding explicit typecasts. The code is based on Microchip reference code so keep changes to a minimal.
Add a demo application for Raspberry Pi with a LAN9252-based EtherCat hat, such as with the SG Electronics Systems EtherBerry.
* fix build warnings * cmake build fixes and linux build files * add travis build file