[Keyboard] Add Southpad Keyboard (#13964)

Co-authored-by: Drashna Jaelre <drashna@live.com>
Co-authored-by: Ryan <fauxpark@gmail.com>

keyboards/matchstickworks/southpad/southpad.h

@@ -0,0 +1,44 @@
+/* Copyright 2021 Logan Butler
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include "quantum.h"
+
+/* This a shortcut to help you visually see your layout.
+ *
+ * The first section contains all of the arguments representing the physical
+ * layout of the board and position of the keys.
+ *
+ * The second converts the arguments into a two-dimensional array which
+ * represents the switch matrix.
+ */
+#define LAYOUT_numpad_6x4_southpaw( \
+				k00, k01, k02, k03, \
+				k10, k11, k12, k13, \
+					k21, k22, k23, \
+				k20, k31, k32, k33, \
+					k41, k42, k43, \
+				k40, k51,   k53  \
+) \
+{ \
+	{ k00,   k01, k02,   k03 },     \
+	{ k10,   k11, k12,   k13 },     \
+	{ k20,   k21, k22,   k23 },     \
+	{ KC_NO, k31, k32,   k33 },     \
+	{ k40,   k41, k42,   k43 },     \
+	{ KC_NO, k51, KC_NO, k53 }      \
+}
+