add CRC32-IEEE checksum

• added some internal helper functions to memory image
• add CRC32-IEEE checksum

migrate to VSCode / PlatformIO file structure

supports both (cross-)build via PlatformIO / VSCode and Makefile

Introduce dynamic memory image

• replace static (huge) RAM buffer by dynamic memory image (proposal from gicking/stm8gal#26)
• fixed several minor bugs and memory leaks

initial release

initial release