Structs for Wire Protocol HTLCs and Commitments

* Structs and wire messages for HTLCs
* Wire protocol for a state machine with no blocking(!!!)
  (I will write the state machine)
  TL;DR: Can do multiple HTLC modifications in-flight, dead simple wire
  protocol. Both sides can update their Commitments unliaterally without
  waiting for the other party's signature. Will have basic/preliminary
  notes in the README
* Added **swp to .gitignore because of vim annoyances

lnwire/htlc_settlerequest.go

@@ -0,0 +1,90 @@
+package lnwire
+
+import (
+	"fmt"
+	"io"
+)
+
+//Multiple Clearing Requests are possible by putting this inside an array of
+//clearing requests
+type HTLCSettleRequest struct {
+	//We can use a different data type for this if necessary...
+	ChannelID uint64
+
+	//ID of this request
+	StagingID uint64
+
+	//Redemption Proofs (R-Values)
+	RedemptionProofs []*[20]byte
+}
+
+func (c *HTLCSettleRequest) Decode(r io.Reader, pver uint32) error {
+	//ChannelID(8)
+	//StagingID(8)
+	//Expiry(4)
+	//Amount(4)
+	//NextHop(20)
+	//ContractType(1)
+	//RedemptionHashes (numOfHashes * 20 + numOfHashes)
+	//Blob(2+blobsize)
+	err := readElements(r,
+		&c.ChannelID,
+		&c.StagingID,
+		&c.RedemptionProofs,
+	)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+//Creates a new HTLCSettleRequest
+func NewHTLCSettleRequest() *HTLCSettleRequest {
+	return &HTLCSettleRequest{}
+}
+
+//Serializes the item from the HTLCSettleRequest struct
+//Writes the data to w
+func (c *HTLCSettleRequest) Encode(w io.Writer, pver uint32) error {
+	err := writeElements(w,
+		c.ChannelID,
+		c.StagingID,
+		c.RedemptionProofs,
+	)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (c *HTLCSettleRequest) Command() uint32 {
+	return CmdHTLCSettleRequest
+}
+
+func (c *HTLCSettleRequest) MaxPayloadLength(uint32) uint32 {
+	//21*15+16
+	return 331
+}
+
+//Makes sure the struct data is valid (e.g. no negatives or invalid pkscripts)
+func (c *HTLCSettleRequest) Validate() error {
+	//We're good!
+	return nil
+}
+
+func (c *HTLCSettleRequest) String() string {
+	var redemptionProofs string
+	for i, rh := range c.RedemptionProofs {
+		redemptionProofs += fmt.Sprintf("\n\tSlice\t%d\n", i)
+		redemptionProofs += fmt.Sprintf("\t\tRedemption Proof: %x\n", *rh)
+	}
+
+	return fmt.Sprintf("\n--- Begin HTLCSettleRequest ---\n") +
+		fmt.Sprintf("ChannelID:\t%d\n", c.ChannelID) +
+		fmt.Sprintf("StagingID:\t%d\n", c.StagingID) +
+		fmt.Sprintf("RedemptionHashes:") +
+		redemptionProofs +
+		fmt.Sprintf("--- End HTLCSettleRequest ---\n")
+}