Package make-initrd-bootchain: Information

- download: rewrited reaction to returned http/ftp status codes.
- don't count whole disk drive with the same first partition.
- don't connect to default router anymore, only suggests.
- checksum: reboot the computer if checksum mismatch.
- waitnet: back to the main menu if network not ready.

- introduce bootchain-waitnet sub-module and function bc_reboot().
- major fixes and improvements around networking boot methods.

- major fixes and improvements around using RAM-disks and tmpfs.
- package documentation reorganized and separated.
- old feature code and logs complete removed.