Fix #2685.
Ensure Longitude initialized with Longitude keeps same wrap_angle by default
Rewrite broadcast quantity using _new_view, so properties are kept
Make _to_own_unit aware of dtype of value coming in
Also ensure NaN are treated properly; add test cases
Speed up check if dtypes same; ensure numpy 1.5 does not fail
Ensure Table.remove_columns works when given a single column name
Update docstring and change log
Merge pull request #2705 from mhvk/longitude-keep-wrapangle

Ensure Longitude initialized with Longitude keeps same wrap_angle by default
Changelog entry that quantity objects can be assigned NaN
Merge pull request #2695 from mhvk/quantity-do-not-prevent-recarray

Bug in Quantity.itemset for NaN values
Merge pull request #2685 from mdboom/votable/name-error

Bug: votable.conesearch fails with `NameError: global name 'votable' is not defined`
Merge pull request #2699 from mhvk/table-remove-columns-single-column

Table.remove_columns on a string
Quantity: Convert numerical objects such as decimal.Decimal to float by default