create /apps/temapltes/ structure, clean up cmake files to use directory name for binary name directly

apps/templates/c/game.c

@@ -0,0 +1,27 @@
+#include "twn_game_api.h"
+#include "state.h"
+
+#include <stdlib.h>
+
+
+void game_tick(void) {
+    /* do state initialization when engine asks for it */
+    /* it could happen multiple times per application run, as game code is reloadable */
+    if (ctx.initialization_needed) {
+        /* application data could be stored in ctx.udata and retrieved anywhere */
+        if (!ctx.udata)
+            ctx.udata = calloc(1, sizeof (struct state));
+    }
+
+    /* a lot of data is accessible from `ctx`, look into `townengine/context.h` for more */
+
+    struct state *state = ctx.udata;
+    ++state->counter;
+}
+
+
+void game_end(void) {
+    /* do your deinitialization here */
+    struct state *state = ctx.udata;
+    free(state);
+}