This patch set:
- Moves memory device parsing to use XML like the rest
- Restructures the entry points of device-only parsing to share
more code
- Adds a function to parse plain XML into a dominfo structure for
times where we don't have a virDomainPtr
- Updates the xml_parse_test program to allow testing of the aforementioned
function, as well as clean up the option parsing to make way for more
features later