Added the []= overloadable operator and implemented it for vector, map, and string

stdlib/map.krak

@@ -29,6 +29,9 @@ obj map<T,U> {
     fun find_index(key: T): int {
         return keys.find_index(key)
     }
+    fun operator[]=(key: T, value: U) {
+        set(key,value)
+    }
     fun set(key: T, value: U) {
         var keyIdx = find_index(key)
         if (keyIdx >= 0) {

stdlib/string.krak

@@ -43,6 +43,12 @@ obj string (Object) {
         var new.construct(data.slice(first,second)): string
         return new
     }
+    fun operator[]=(index: int, toSet: char) {
+        data[index] = toSet
+    }
+    fun set(index: int, toSet: char) {
+        data.set(index, toSet)
+    }
     fun length():int { return data.size; }
 
     fun operator=(str: char*): void {

stdlib/vector.krak

@@ -140,6 +140,9 @@ obj vector<T> (Object) {
         return -1;
     }
 
+    fun operator[]=(index: int, dataIn: T) {
+        set(index, dataIn)
+    }
     fun set(index: int, dataIn: T): void {
         if (index < 0 || index  >= size)
             return;