Ensure that non-numeric property types work with effectValueAtLocalTime.

Non-numeric properties don't have specific entries in the propertyTypes
dictionary. Rather than looking properties up directly, using getType
ensures the generic type entry is used when none other is available.
Review comments
Merge pull request #591 from shans/fixNonNumeric

Ensure that non-numeric property types work with effectValueAtLocalTime.
Merge branch 'experimental-rebase' into experimental