Backport get_memory changes to 2.1

These changes were committed to master 5 days ago. It would be handy/useful to have them in 2.1 also. Most of it is var name changes for clarification, but there are these functional things:
config.console.inc and rc.bootup - comparisons to $g['minimum_ram_warning'] (101 MB) now use $physmem (e.g. 235MB on Alix). Clearly the "101" global was not meant to be compared with $realmem (256MB on Alix, 128MB on a "really 128MB system).
pfsense-utils.inc - calculate state table based on $physmem, the actual memory that FreeBSD has to work with.