Reworked Toy_String as a union, enabled -Wpedantic

Toy now fits into the C spec.

Fixed #158

Addendum: MacOS test caught an error:

error: a function declaration without a prototype is deprecated in all versions of C

That took 3 attempts to fix correctly.

Addendum: 'No new line at the end of file' are you shitting me?

tests/standalone/hash_generator_1.c

@@ -8,7 +8,7 @@ static unsigned int hashUInt(unsigned int x) {
     return x;
 }
 
-int main() {
+int main(void) {
     //print the index/hash pairs
     for (unsigned int i = 0; i < 100; i++) {
         unsigned int h = hashUInt(i);