Quarks2.install fetches if needed. Also add more error checks
standardise Quarks2 dict keys as strings or floats
Quarks2.fromQuarks1 convenience method
update example
Quarks2:installed method
some logic to decide whether to install or upgrade a quark
Quarks2 now able to use a remote default sourceslist
ensure folders exist
Quarks2:pr_chooseBestVersion, and other updates part-based on miguel's pull request 4