Multiboot kernels

FreeLDR ideology implies that core bootloader functionality comprises only multiboot kernels loading. Custom kernel types loading can be also supported, but this functionality must be separated from the loader core. So, it were decided to move a custom kernel support to an intermediate layer above the loader core. They are implemented as separate multiboot kernels. So, the core loader loads a custom kernel booter and a number of required modules it needs. Then, the booter implements an algorythm of some kernel loading. The core bootloader must not know about details of a specific OS boot process. These details are separated by a specific OS booter from the core loader.