LLViewerRegion WIP: Added all headers that are dragged in.

Most in particular llevents.h, which comes along with
the demand that the old events in llevent.h are put
in a namespace LLOldEvents. Made all changes necessary
to compile the rest of the code again (without changing
the actual code: it's still using the old events).

This patch also removes LLStopWhenHandled and LLStandardSignal
from indra/llui/llnotifications.h because those are
moved to llevents.h. That seems to be the only change
to indra/llui/llnotifications.h that isn't floater related,
so I left the rest of that file alone.

indra/llcommon/lleventapi.cpp

@@ -0,0 +1,77 @@
+/**
+ * @file   lleventapi.cpp
+ * @author Nat Goodspeed
+ * @date   2009-11-10
+ * @brief  Implementation for lleventapi.
+ * 
+ * $LicenseInfo:firstyear=2009&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library 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;
+ * version 2.1 of the License only.
+ * 
+ * This library 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 library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+// Precompiled header
+#include "linden_common.h"
+// associated header
+#include "lleventapi.h"
+// STL headers
+// std headers
+// external library headers
+// other Linden headers
+#include "llerror.h"
+
+LLEventAPI::LLEventAPI(const std::string& name, const std::string& desc, const std::string& field):
+    lbase(name, field),
+    ibase(name),
+    mDesc(desc)
+{
+}
+
+LLEventAPI::~LLEventAPI()
+{
+}
+
+LLEventAPI::Response::Response(const LLSD& seed, const LLSD& request, const LLSD::String& replyKey):
+    mResp(seed),
+    mReq(request),
+    mKey(replyKey)
+{}
+
+LLEventAPI::Response::~Response()
+{
+    // When you instantiate a stack Response object, if the original
+    // request requested a reply, send it when we leave this block, no
+    // matter how.
+    sendReply(mResp, mReq, mKey);
+}
+
+void LLEventAPI::Response::warn(const std::string& warning)
+{
+    LL_WARNS("LLEventAPI::Response") << warning << LL_ENDL;
+    mResp["warnings"].append(warning);
+}
+
+void LLEventAPI::Response::error(const std::string& error)
+{
+    // Use LL_WARNS rather than LL_ERROR: we don't want the viewer to shut
+    // down altogether.
+    LL_WARNS("LLEventAPI::Response") << error << LL_ENDL;
+
+    mResp["error"] = error;
+}