Move scriptapi to separate folder (by sapier)

On the lua side, notably minetest.env:<function>(<args>) should now
be replaced by minetest.<function>(<args>).
The old way is and will stay supported for a long time.

Also:
Update and clean up lua_api.txt (by celeron55)
Move EnvRef to lua and remove add_rat and add_firefly (by kahrl)
Add separate src/util/CMakeLists.txt, other minor fixes (by kahrl)

src/script/lua_api/l_base.h

@@ -0,0 +1,63 @@
+/*
+Minetest
+Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef L_BASE_H_
+#define L_BASE_H_
+
+#include "biome.h"
+#include "common/c_types.h"
+
+extern "C" {
+#include "lua.h"
+}
+
+extern struct EnumString es_BiomeTerrainType[];
+
+class ScriptApi;
+class Server;
+class Environment;
+
+typedef class ModApiBase {
+
+public:
+	ModApiBase();
+
+	virtual bool Initialize(lua_State* L, int top) = 0;
+	virtual ~ModApiBase() {};
+
+protected:
+	static Server* getServer(      lua_State* L);
+	static Environment* getEnv(    lua_State* L);
+	static bool registerFunction(	lua_State* L,
+									const char* name,
+									lua_CFunction fct,
+									int top
+									);
+} ModApiBase;
+
+#if (defined(WIN32) || defined(_WIN32_WCE))
+#define NO_MAP_LOCK_REQUIRED
+#else
+#include "main.h"
+#include "profiler.h"
+#define NO_MAP_LOCK_REQUIRED ScopeProfiler nolocktime(g_profiler,"Scriptapi: unlockable time",SPT_ADD)
+//#define NO_ENVLOCK_REQUIRED assert(getServer(L).m_env_mutex.IsLocked() == false)
+#endif
+
+#endif /* L_BASE_H_ */