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/newview/CMakeLists.txt

@@ -82,6 +82,7 @@ include_directories(
 set(viewer_SOURCE_FILES
     NACLantispam.cpp
     aihttpview.cpp
+    aixmllindengenepool.cpp
     aoremotectrl.cpp
     ascentfloatercontactgroups.cpp
     ascentkeyword.cpp
@@ -598,6 +599,7 @@ set(viewer_HEADER_FILES
 
     NACLantispam.h
     aihttpview.h
+    aixmllindengenepool.h
     aoremotectrl.h
     ascentfloatercontactgroups.h
     ascentkeyword.h