#227 doxygenfilter fails to document variables

[HaJo Schatz]

Reproducable with the example included in doxygenfilter
1.01: Create the html-doc of the example, during the
doxygen (1.4.4) run, warnings are produced:
----------------------------
Searching for enumerations...
DocumentationDemo.pm:31 Warning: Documentation for
undefined enum `Keys' found.
Searching for member function documentation...
DocumentationDemo.pm:36 Warning: documented function
`Keys a' was not defined.
DocumentationDemo.pm:39 Warning: documented function
`b' was not defined.
-----------------------------
Variables do not appear at all in the resulting doc.