eclipse: add Eclipse IDE for C/C++ Developers 4.2

If you upgrade from 3.7 you might get errors like these:

In the Package Explorer:
 Could not create the view: org.eclipse.jdt.ui

And some other stuff in the Error Log; "Unable to resolve plug-in [...]"

The solution is to delete your eclipse workspace (or just the hidden
setting files in there, if you have important user data).
Merge pull request #465 from bjornfor/eclipse

eclipse: add Eclipse IDE for C/C++ Developers 4.2