Ignore build directory.

git-svn-id: file:///srv/svn/repos/tudatCore/trunk@179 f1678324-46bc-11e1-bac6-37db1e3cb3f9
Update Doxygen config file to 1.8.7 and ignore Documentation/ sub-directory.

git-svn-id: file:///srv/svn/repos/tudatCore/trunk@180 f1678324-46bc-11e1-bac6-37db1e3cb3f9