Fix a couple of comments (#386)

msg.go

@@ -58,7 +58,7 @@ var (
 	ErrTruncated     error = &Error{err: "failed to unpack truncated message"} // ErrTruncated indicates that we failed to unpack a truncated message. We unpacked as much as we had so Msg can still be used, if desired.
 )
 
-// Id, by default, returns a 16 bits random number to be used as a
+// Id by default, returns a 16 bits random number to be used as a
 // message id. The random provided should be good enough. This being a
 // variable the function can be reassigned to a custom function.
 // For instance, to make it return a static value:

server.go

@@ -147,7 +147,7 @@ func (mux *ServeMux) match(q string, t uint16) Handler {
 				b[i] |= ('a' - 'A')
 			}
 		}
-		if h, ok := mux.z[string(b[:l])]; ok { // 'causes garbage, might want to change the map key
+		if h, ok := mux.z[string(b[:l])]; ok { // causes garbage, might want to change the map key
 			if t != TypeDS {
 				return h
 			}