Finish implementing initial objects

lib/structs/Bitmasks.dart

@@ -1,7 +1,27 @@
-class BitMask {}
-
-abstract class MaskEnum {
-  int getValue();
-
-  List<MaskEnum> getValues();
+mixin EFlags on Enum {
+  int get value => 1 << index;
+}
+
+/// A simple universal bitmask object
+class BitMask {
+  int _mask = 0;
+
+  BitMask(this._mask);
+
+  void setBit(int bit) {
+    _mask |= bit;
+  }
+
+  void unsetBit(int bit) {
+    _mask ^= bit;
+  }
+
+  int get value => _mask;
+
+  factory BitMask.of(int? val) {
+    if (val == null)
+      return BitMask(0);
+    else
+      return BitMask(val);
+  }
 }