Add hardware currently deployed by Czech ISPs and update existing devices

[Troll338cz]

Comtrend GRG-4284, GRG-4362 and Tenda HG1

• HW info, flash layout
• Device specific telnet access

Iskratel Innbox X24:

• HW info, flash layout
• Reading and writing GPON SN

Kaon PM1191:

• Some HW info
• Dual image partitioning
• Reading and writing GPON SN/PLOAM and LOID

Zyxel PMG5100-T0 and Sercomm FG1000R:

• Add missing information about hardware from boot logs and disassembly.

Sercomm FGS202:

• Correct flash and RAM sizes, document serial and SFP pinout
• Add one of Orange France firmware versions.
• Document enabling telnet on LAN side, reading PLOAM password from telnet.
• Add tool for environment CRC generation and decrypting PLOAM from flash dump.
• Flashing the stick with sercomm-recovery.