Moved tests + Added more tests + Added memory testing to actions

tests/ev_str/replace_first.c

@@ -0,0 +1,20 @@
+#define EV_STR_IMPLEMENTATION
+#include "ev_str.h"
+
+#include <assert.h>
+#include <string.h>
+
+int main(void)
+{
+  evstring text = evstring_new("Hello, Hello!");
+  assert(text != NULL);
+
+  evstring rep_str = evstring_replaceFirst(text, evstr("Hello"), evstr("Bye"));
+  assert(rep_str != NULL);
+  assert(strcmp(rep_str, "Bye, Hello!") == 0);
+
+  evstring_free(rep_str);
+  evstring_free(text);
+
+  return 0;
+}