BSON should convert Rat to Num where possible

[lefth]

When floats/doubles are serialized to JSON then converted to Perl numbers, they're re-interpreted as Rat. Rat can't be handled by the database and gives an error.

Suggested solution: if Rat can be converted to Num without loss of data, do it. This will let BSON work with data that has been serialized without truncating data. (Verify that $n.Num.Rat == $n first.)

It would also be nice if BSON had an option that enabled truncating all floating point types to a type that is allowed in the database, even if some precision is lost. Perhaps $doc.accept-numbers, analogous to accept-hash which permits order information loss.

#23

[MARTIMM]

PR is merged, thanks Dan