synchronise with the template

- use the version of audio management which doesn't crash the
application if something goes wrong
- include colour32
- update error management to be more reflective of the one defined in
the template
- modify the renderer functions to be more reflective of the template
- modify the game functions to be more reflective of the template (& use
a more failproof method of initializing)
- add gametime
- remove set_gamestatus logic and just use a run boolean in gamedata
- remove emscripten preprocessors as those haven't really been used

src/game/gametime.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <time.h>
+
+#include "../util/attributes.h"
+
+typedef struct {
+    struct timespec ts; // stores the time at the current update
+    double sec;         // stores the current time in seconds
+    float scale;        // multiplier for the time calculation, default value is 1.0
+    float delta;        // the time that it took between updates
+} gametime;
+
+// initializes the gametime struct
+atrb_const static inline gametime gametime_new(void) {
+    struct timespec ts;
+    timespec_get(&ts, TIME_UTC);
+
+    return (gametime){
+        ts,
+        0.0,
+        1.0F,
+        0.0F,
+    };
+}
+
+// updates the internal variables
+static inline void gametime_update(gametime* gt) {
+    struct timespec ts;
+    timespec_get(&ts, TIME_UTC);
+    gt->sec = (double)ts.tv_nsec * 1e-9;                                    // calculate the current time in seconds
+    gt->delta = ((double)(ts.tv_nsec - gt->ts.tv_nsec) * 1e-9) * gt->scale; // calculate how much time has passed between this and last frame
+    gt->ts = ts;                                                            // update the game's timespec
+}
+
+// gets how many times the game updates per second
+atrb_const static inline float gametime_get_ups(gametime* gt) {
+    return 1.0F / gt->delta;
+}