Bug-fix release v1.4.2

Changelog:

• Major memory leak inside IPMB_RXTask fixed;
• Add a new IPMI OEM command to check the available heap;
• Fix linking errors with GCC 10 (-fno-common);
• Vector checksum calculation to comply with the internal bootloader boot check;
• Erase the upgrade firmware region after a successful upgrade to avoid re-flashing upon another reset.