Features

New write_flash --erase-all ... option to erase all flash before writing (single command). (#344)
Support patching the SHA256 digest of the ELF file into the binary (available in ESP-IDF via app description APIs)
Make calling esptool module functions and esptool.main() more Python-friendly (all functions clean up open files correctly, main(...) can take an optional argument with a command line formatted as a list.) (#341)

Bug Fixes/Changes

Fix crash due to unimplemented write timeout on RFC2217 ports
elf2image no longer adds empty ELF sections (zero length) to the .bin file
elf2image fails with a proper error if an ELF file contains more than 16 loadable sections
Improve error message if list_ports is missing from pyserial (#350)
Fix some write_flash timeouts writing large but highly compressible payloads

Fix bug where flashing with stub would fail if ESP8266 was in deep sleep immediately beforehand. (#351)

Support for reading/writing efuses when 3/4 Coding Scheme is set details.
espefuse.py supports displaying and setting a custom MAC address in BLK3 of efuse
espsecure.py can now verify signatures with raw binary key file as well as PEM formatted key file (#357)

Workaround a mapping bug in the ESP-IDF bootloader (if IROM/DROM segment ended less than 0x20 bytes after a page boundary, older ESP-IDF bootloaders would not map the final page correctly).
Reformat espefuse.py summary output (includes: read-only efuses now display value ? not 0, byte order of keys shown for BLK1,BLK2 are now shown in software order not the reversed byte order used by hardware cryptographical modules.)
espsecure.py: Fix Python 3 compatibility issues (includes #369 #382)

Special thanks to @Callahan93 and @borro0 for contributing to this release.