Renamed GetCurrentBlockNumber to GetLatestBlockNumber

The intention of the function is to return the most recent block that
was mined (added to the chain) - also called a "tip".
Replacing `Current` with `Latest` seems accurate and should reduce the
confusion, as `current` may suggest the block that is currently being
mined.

Author: nkuba

pkg/bitcoin/chain.go

@@ -20,9 +20,9 @@ type Chain interface {
 	// rejected eventually.
 	BroadcastTransaction(transaction *Transaction) error
 
-	// GetCurrentBlockNumber gets the number of the current block. If the
-	// current block was not determined, this function returns an error.
-	GetCurrentBlockNumber() (uint, error)
+	// GetLatestBlockNumber gets the height of the latest block (tip). If the
+	// latest block was not determined, this function returns an error.
+	GetLatestBlockNumber() (uint, error)
 
 	// GetBlockHeader gets the block header for the given block number. If the
 	// block with the given number was not found on the chain, this function

pkg/bitcoin/electrum/electrum.go

@@ -27,7 +27,7 @@ func (c *Client) BroadcastTransaction(
 	panic("not implemented")
 }
 
-func (c *Client) GetCurrentBlockNumber() (uint, error) {
+func (c *Client) GetLatestBlockNumber() (uint, error) {
 	// TODO: Implementation.
 	panic("not implemented")
 }