Add regex and CAN, improve UART, and more. py core: - add basic regex support using re1.5 library - replace zlibd with uzlib - compiler returns proper exception on SyntaxError - proper context saving for eval/exec - use mp_[u]int_t in most places instead of [u]int - better ARM support in native emitter - autodetect machine endianness - better big endian support - memory errors from locked gc can be reported - more robust lexer when out of memory - rename modules to begin with u-, and add module weak links - more native binops in viper emitter - native pointers with load+store in viper - fix GC realloc so that chunks are shrunk correctly - compiler optimisations for constant if/while conds - add kwargs for builtin open() and FileIO - enable unicode on windows stmhal port: - add basic CAN bus support - overhaul UART class to use read/write - add NRF24L01 driver (in pure Python) - pyb.freq can change SYSCLK - add pyb.stop and pyb.standby - can set Timer freq using float - Timer supports complementary channel and deadtime - add retry for SD card init