More formatting options for serialization

[spyoungtech]

Right now, serialization supports some basic configuration of the key/item separators (e.g., for compact formatting) as well as for indent level/pretty printing, similar to capabilities offered by serde_json.

However, I want to add more flexibility to this including:

1. Preference of quote character (single quote or double quotes) for string values
2. Ability to prefer bare unquoted identifiers for object keys
3. Possibly some way to control serialization of number values (e.g., convert floats to integers when no loss would occur)