FreeDOS kernel version 2.43

Please review git history for full change log.
Some changes include now support building with GCC-ia16, CHAIN command in config.sys, various fixes, new setver capabilities

Source and 8086 compatible builds provided, f16 only supports FAT12/FAT16, while f32 also supports FAT32 formatted disks (both 8086).

kernel.zip provides a FreeDOS package, 8086 version with FAT12/FAT16 and 386 version with FAT12/FAT16/FAT32

ke2043_rufus is a 386 compiled version with FAT12/16/32 support and FORCELBA enabled