Add proper documentation to the Constructor class

This works like other classes and removes the template versions of the
class, giving Doxygen a good clean example.
Upgrade Doxyfile and fix readme generation

Newer versions of Doxygen were having hard times with the leading '*' in
README.doxyfile so had to fix that file's generation.
Version bump, release 1.5.2
Update annoucement with recent chagnes