import_extra_data() has special handling for converting string representations

of Boolean and integer values in extra_data to their respective data types,

but lacks handling for floating point values. This trickles up so that JSON

responses to API queries show floating point values as strings rather than

numeric values. This issue is fixed by adding special handling for floating

point data types.
JSON snippets of a response to a review request draft update are attached to

illustrate the before and after behavior. Notice the floating point fields

are quoted (e.g. represented as strings) in the before case.

Added a new unit test which failed prior to this fix.
Ran unit tests.