setup the skeletal structure for Eq, Comp and Gate.

implement strip/bus eq on commands.

internal/xair/gate.go

@@ -0,0 +1,9 @@
+package xair
+
+type Gate struct {
+	client *Client
+}
+
+func newGate(c *Client) *Gate {
+	return &Gate{client: c}
+}