New `stringify` configurability options?

[adamhamlin]

This is just a couple suggestions for new configurable options for JSON5.stringify(...):

• Configure inclusion of trailing comma
• Configure inclusion of whitespace "padding" for single line output. For example, allow to output { key1: 'value1', key2: 'value2' } instead of {key1:'value1',key2:'value2'}.

Thanks for your consideration!