Compatible native token denom

for Smart Contracts to issue native tokens and easy IBC adoption 
 
gnolang#393

pkgs/std/coin.go

@@ -617,8 +617,9 @@ func (coins Coins) Sort() Coins {
 // Parsing
 
 var (
-	// Denominations can be 3 ~ 16 characters long.
-	reDnmString = `[a-z][a-z0-9]{2,15}`
+	// Denominations can be 3 ~ 128 characters long and support letters, followed by either
+	// a letter, a number or a separator ('/', ':', '.', '_' or '-').
+	reDnmString = `[a-zA-Z][a-zA-Z0-9/:._-]{2,127}`
 	reAmt       = `[[:digit:]]+`
 	reDecAmt    = `[[:digit:]]*\.[[:digit:]]+`
 	reSpc       = `[[:space:]]*`