Cosmetic \n after each command is entered at the boot2 prompt.
Rename boot2 'dk' for 'direct kernel' to 'dl' for 'direct load': we will
generally load loader, rather than the kernel, here.
Update BERI boot-loader definition of the location of the boot file system
in flash (previously known as 'kernel').

Add a convenience definition of the kernel load address -- which for now is
the same as the boot2 address due to our using Miniboot to boostrap boot2.
Complete relocation of common.ldscript from the the boot2 directory to one
where it is easily used by loader, as well.  Use it from loader.ldscript.
Rename include guards for cfi.h to match filename.
Add first cut at a boot2/loader SD Card micro-driver; untested.
Hook up untested SD Card micro-driver to boot2.
Build SD card micro-driver as part of loader, but don't yet use it.