Move sourced/shared scripts to boot-*-common
Rearrange common definitions in each boot script to make them more
similar
Add common support for %ARCH% substitutions in DI_WWW_HOME
Fix boot-alpha to use which_deb when looking for aboot
Merge mips* together, using boot-mips-common
Previous changes enabled gzip compressed Linux kernels, but not 100%
sure that it works on all systems. Disable this compression for now.
Switch hppa to use xorriso by default instead of mkisofs. Xorriso
supports kernel command lines to be up to 1023 bytes, better than
mkisofs. mkisofs only supports the older palo version 4 header format
which can hold only 127 characters which might be too small.
John Paul Adrian Glaubitz
Steve McIntyre