move reverts/restores of old upstream behaviour to an own subdir
consolidate network related patches into 15_networking_grml.patch

11_dhcphostname.patch, 16_nodhcp.patch and 36_support_dhcp_bootoption.patch
would not work without it anyways.

moved grml-specific code from 26_support_dns_bootoption.patch to 15_networking_grml.patch