Resolves #208 Gauge card

lib/cards/card.class.dart

@@ -0,0 +1,64 @@
+part of '../main.dart';
+
+class HACard {
+  List<EntityWrapper> entities = [];
+  List<HACard> childCards = [];
+  EntityWrapper linkedEntityWrapper;
+  String name;
+  String id;
+  String type;
+  bool showName;
+  bool showState;
+  bool showEmpty;
+  int columnsCount;
+  List stateFilter;
+  List states;
+  List conditions;
+  String content;
+  String unit;
+  int min;
+  int max;
+  Map severity;
+
+  HACard({
+    this.name,
+    this.id,
+    this.linkedEntityWrapper,
+    this.columnsCount: 4,
+    this.showName: true,
+    this.showState: true,
+    this.stateFilter: const [],
+    this.showEmpty: true,
+    this.content,
+    this.states,
+    this.conditions: const [],
+    this.unit,
+    this.min,
+    this.max,
+    this.severity,
+    @required this.type
+  }) {
+    if (this.columnsCount <= 0) {
+      this.columnsCount = 4;
+    }
+  }
+
+  List<EntityWrapper> getEntitiesToShow() {
+    return entities.where((entityWrapper) {
+      if (entityWrapper.entity.isHidden) {
+        return false;
+      }
+      if (stateFilter.isNotEmpty) {
+        return stateFilter.contains(entityWrapper.entity.state);
+      }
+      return true;
+    }).toList();
+  }
+
+  Widget build(BuildContext context) {
+    return CardWidget(
+      card: this,
+    );
+  }
+
+}