Rewrite the entire code-base

The following changes are focused upon:
- Modularity
- Doing away with globals
- No heap allocations
- Better command line interface
- Switch from Xlib to XCB
- More verbose type definitions
- Implement a single-file config by utilising X-macros

src/cli.c

@@ -0,0 +1,30 @@
+#include "cli.h"
+
+#include <getopt.h>
+#include <stdbool.h>
+#include <stdio.h>
+
+int cli_init(cli_arguments *const args, const char *const argv[],
+             const int argc) {
+    args->is_debug_mode = false;
+
+    int opt = -1;
+    opterr = 0;  // Suppress getopt's built-in invalid opt message
+    while ((opt = getopt(argc, (char *const *)argv, "dh")) != -1) {
+        switch (opt) {
+            case 'd':
+                args->is_debug_mode = true;
+                break;
+            case 'h':
+                // fall through
+            case '?':
+                (void)fprintf(stderr, "error: unknown option `-%c'\n", optopt);
+                // fall through
+            default:
+                (void)fprintf(stderr, "usage: %s [-d]\n", BINARY);
+                return 1;
+        }
+    }
+
+    return 0;
+}