Case sensitivity

[mastercoms]

Hi, wonderful library! I've noticed that for the reference VDF implementation, keys are case-insensitive. However, keys in this library are case-sensitive. Could a parse option be added to make options case insensitive? Perhaps by just adding toLowerCase for all keys. This would suffice for my usage, at least.

[joekiller]

I agree this would be helpful. For reference, you can see that valve utilizes a tolower function