Start beautifying the code

* Split out SPI and display (a little)
* Use more of the common Macros
* Remove wasted bytes from notomono font
* Create a mock "menu"

font.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2019  Max Regan
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "font.h"
+
+const struct glyph *glyph_for_char(const struct font *font, char c)
+{
+    // TODO: This is almost the least efficient way imaginable to implement this
+    for (int i = 0; i < font->max; i++) {
+        const struct glyph *g = font->glyphs[i];
+        if (g == NULL) {
+            continue;
+        }
+
+        if (g->glyph == c) {
+            return g;
+        }
+    }
+
+    return NULL;
+}