Add AIXMLLindenGenepool - redo of archetype export/import using AIXML*.

In order to remove code duplication, and as prove of concept,
I redid the linden_genepool archetype export and import (from the Edit
Appearance Floater), using AIXML and AIAlert.

The import/export code did shrink significantly, and became a lot
simpler. Although a new file pair (aixmllindengenepool.{cpp,h}) is
added to define the (de)serialization of the linden_genepool XML format,
that code is now centralized in one place, and still a lot simpler.

As a bonus however, every possible error is now semi-automatically
reported to the user with all details that might help to overcome
the problem, like file names and system errors.

indra/llappearance/llviewervisualparam.cpp

@@ -143,6 +143,12 @@ BOOL LLViewerVisualParam::setInfo(LLViewerVisualParamInfo *info)
 	return TRUE;
 }
 
+//virtual
+std::string LLViewerVisualParam::getDumpWearableTypeName(void) const
+{
+  return LLWearableType::getTypeName(LLWearableType::EType(getInfo()->mWearableType));
+}
+
 /*
 //=============================================================================
 // These virtual functions should always be overridden,