* FundingSignAccept and FundingSingComplete had *[]btcec.Signature and
instead it's now []*btcec.Signature to match other slice types.
* Refactored lnwire's when doing readElement/writeElement on slices
* Added field
* Renamed FundingAmount and ReserveAmount to specify in FundingRequest
and FundingResponse that it is for RequesterFundingAmount or
ResponderFundingAmount
* Added PaymentAmount field to FundingRequest
* Added MinDepth field to FundingRequest and FundingResponse
* Fixed .Serialize() to show inputs/etc. only if there are fields
available (prevents trying to dereference nil value)
* Add a bunch of Validate() conditions
* MASSIVE REFACTOR of tests (removed tons of redundancy)
