Log: scheduler: sort node names numerically and case-insensitively

Previously, node names were sorted (for display, etc.) alphabetically,
which means that names would display like:

Clone Set: clone2 [clone2rsc]

Started: [ node10 node11 node2 node3 node4 ]

Now, if both names contain digits at the same location, that portion is
compared numerically. Also, non-digits are compared case-insensitively,
since node names (like DNS names) are intended to be case-insensitive.
The same display is now:

Clone Set: clone2 [clone2rsc]

Started: [ node2 node3 node4 node10 node11 ]