This mapper is responsible for the lookup of templates for the Layout
It tries to look in various packages for a match:
1. about,directions,Driving.vm <- exact match
2. about,directions,Default.vm <- package match, Default name
3. about,Default.vm <- stepping up in the hierarchy
4. Default.vm <- The name configured as default.layout.template
in the corresponding Templating Engine
author: Henning P. Schmiedehausen version: $Id: LayoutTemplateMapper.java 534527 2007-05-02 16:10:59Z tv $