Add hybridcd target

See title...

Currently (as of revision 66051) the hybrid cd is the following:

• the full contents of the bootcd under the subdirectory "bootcd\" (note that booting the bootcd in ramdisk doesn't work at the moment...)
• the full contents of the livecd under the subdirectory "livecd\". This is for being able to have livecd functionality without RamDisk (in case your test computer does not have enough RAM).
• the image livecd.iso that can be mounted as RamDisk (if you have enough RAM...)
• in the "loader\" there is the bare minimum to boot the hybrid cd.
• and the usual files (icon, autorun...)
• and finally a suitable freeldr.ini configuration file.

When in the future we will be able to transform the livecd.iso into some kind of .img HDD flat image things would be simpler a bit I think...