Adjust some comments.
Implement StringifyMarkerDump for WAL markers.

This implements a LegendReader class inheriting from TRI_shaper_t,
to allow for TRI_StringifyArrayShapedJson to work.
Merge branch 'mjmh' of ssh://github.com/triAGENS/ArangoDB into mjmh
Take care of primitive shapes in LegendReader.
Remove an unused "using namespace triagens;".