Add all grid properties as variables

For use in the templates.xml file, all of our
properties must also be available as variables
before loading the templates.
Revert "memory.py: add support for 'append'"

This reverts commit 16cf2938898e4b935e73f516fb69a123245543d4.
Return map from get_memory_settings

The `<option/>` element does not handle splitting
on whitespace, so there must be a number of properties
rather than one large one.
Append 'm' for values in MB