JavaDoc environment variables enhancement request

Some usefull values are missing in the contextual environment
variables available in JavaDoc support (see
de.hunsicker.jalopy.storage.Environment.Variable). It would be usefull
to get these values as well:

- class: name of the current class or interface without package (at least
in class and interface context);

- year: current full year (at least in class and interface context);

- date: the current date (at least in class and interface context).

The date format can be a problem: maybe a format string (i.e.
SimpleDateFormat string) could be added to the date reference? For
example:

Date: $date:yyyy/MM/dd$

Then the "year" variable wouldn't be necessary.