PHLEGM v8 firmware cache for CBM-3016B

No ROM binaries are shipped by PHLEGM.
Slots, addresses, byte lengths, CRC32 checksums and download URLs are in firmware.config.phlegm.
With Networking enabled, missing firmware is fetched and verified before machine startup.
Hardware profile: European CBM 3016B, BASIC 2, business keyboard, 40x25 TTL, no CRTC.
RAM address range: $0000-$3FFF; memory size: 16 KiB.
Firmware slots: 5
