plugin names hanging around despite being deprecated. These definiations
confused the make install/make instclean so it tried to link a non existant
library. Have removed old definitions and everything intalls properly once
more:-)
for settings options in osgDB::Registry, and added the paramter to all of the
reaader/writer plugins. The Options structure by default has an string attached
for packing basic options, however, it also can be subclassed to encapsulate
any users defined option data. In the later case both the client code *and*
the plugin need to be aware of subclass, the plugin will need to use
dynamic_cast<> to assertain its type.
