Add movement relative to time

Previously movement was based on frames rather than
time. I added time_get_dt() function for getting time
since last frame and changed rotation speed to use this
function.

Signed-off-by: Piotr Krygier <piotrkrygier@everyonecancode@xyz>

utilities/time_utils.h

@@ -12,6 +12,13 @@
 #ifndef TIME_UTILS_H_
 #define TIME_UTILS_H_
 
+#include "commons.h"
+
+rse_err_t time_init(void);
+void time_update(void);
+
 double time_get_sec_from_start(void);
 
+double time_get_dt(void);
+
 #endif // !TIME_UTILS_H_