In particular, do not use com.sun.javadoc deprecated since Java 9 and
finally removed in Java 13, to allow the tests to run under modern JRE.
They don't run under Java 8 and earlier any more, but this shouldn't be
a huge problem nowadays and as SWIG output is independent from the Java
version used, it's enough to test it with modern Java versions.
Note that the tests themselves were changed only in the most minimal
way, to adapt them to the new way of running javadoc (which is now also
integrated into CommentParser itself instead of being duplicated in
every test).
To correctly parse Doxygen post-comments after the trailing comma,
switch to right recursion in "enumlist" production rule definition: this
does consume more stack space when parsing, but makes the rules much
easier to write and to understand and hopefully shouldn't result in any
problems with real code (which shouldn't have thousands of enums items
in it).
Closes#1514.
Vadim Zeitlin