Use x-macros to generate standard expression visualization classes

All classes which are trivial to replace with the new technique are
replaced.
Remove some unused headers and fix test nodes initialization in V.base
Update README.md to include a link to ETH
Clarify some code style issues in the documentation
Add a script to simplify publishing the documentation
Add a virtual method that returns the class name to itemMacros
Introduce a lightweight option to register grid based offset providers
Enhance the Adapter framework with default adapter classes
Use the GridBasedOffsetProvider as a default adapter

This reduces the amount of manual provider registrations that needs to
be done.
Reduce the necessary string offset provider registrations even more
Remove unnecessary functionality from GridBasedOffsetProvider
Avoid showing PLUGINNAME in the Eclipse import projects dialog
Ignore object_script.* files automatically generated by qmake
Use repository .gitignore instead of per project settings.
Add node and item initialization registries to the plug-in generator
Merge pull request #14 from lukedirtwalker/oomodel_enhancements

Oomodel enhancements