Entities redesign and a few ERM features

* Made most Handlers derived from CHandlerBase and moved service API there.
* Declared existing Entity APIs.
* Added basic script context caching
* Started Lua script module
* Started Lua spell effect API
* Started script state persistence
* Started battle info callback binding
* CommitPackage removed
* Extracted spells::Caster to own header; Expanded Spell API.
* implemented !!MC:S, !!FU:E, !!FU:P, !!MA, !!VR:H, !!VR:C
* !!BU:C, !!BU:E, !!BU:G, !!BU:M implemented
* Allow use of "MC:S@varName@" to declare normal variable (technically v-variable with string key)
* Re-enabled VERM macros.
* !?GM0 added
* !?TM implemented
* Added !!MF:N
* Started !?OB, !!BM, !!HE, !!OW, !!UN
* Added basic support of w-variables
* Added support for ERM indirect variables
* Made !?FU regular trigger
* !!re (ERA loop receiver) implemented
* Fixed ERM receivers with zero args.

lib/events/ObjectVisitStarted.cpp

@@ -0,0 +1,67 @@
+/*
+ * ObjectVisitStarted.cpp, part of VCMI engine
+ *
+ * Authors: listed in file AUTHORS in main folder
+ *
+ * License: GNU General Public License v2.0 or later
+ * Full text of license available in license.txt file, in main folder
+ *
+ */
+#include "StdInc.h"
+
+#include "ObjectVisitStarted.h"
+
+#include <vcmi/events/EventBus.h>
+
+
+namespace events
+{
+
+SubscriptionRegistry<ObjectVisitStarted> * ObjectVisitStarted::getRegistry()
+{
+	static std::unique_ptr<Sub> Instance = make_unique<Sub>();
+	return Instance.get();
+}
+
+void ObjectVisitStarted::defaultExecute(const EventBus * bus, const ExecHandler & execHandler,
+	const PlayerColor & player, const ObjectInstanceID & heroId, const ObjectInstanceID & objId)
+{
+	CObjectVisitStarted event(player, heroId, objId);
+	bus->executeEvent(event, execHandler);
+}
+
+CObjectVisitStarted::CObjectVisitStarted(const PlayerColor & player_, const ObjectInstanceID & heroId_, const ObjectInstanceID & objId_)
+	: player(player_),
+	heroId(heroId_),
+	objId(objId_),
+	enabled(true)
+{
+}
+
+PlayerColor CObjectVisitStarted::getPlayer() const
+{
+	return player;
+}
+
+ObjectInstanceID CObjectVisitStarted::getHero() const
+{
+	return heroId;
+}
+
+ObjectInstanceID CObjectVisitStarted::getObject() const
+{
+	return objId;
+}
+
+bool CObjectVisitStarted::isEnabled() const
+{
+	return enabled;
+}
+
+void CObjectVisitStarted::setEnabled(bool enable)
+{
+	enabled = enable;
+}
+
+
+}