(Jo�o Assirati): add the ability to inverse-search a dvi file.

(Jo�o Assirati): add the ability to inverse-search a dvi file.
To use, you'll need either to run 'latex --src-specials' or, if your version
of latex isn't up to the task, to use the srcltx package. Further, your
vi viewer must be up to the task. xdvi 22.38 or the kde 3 version of kdvi.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@7917 a592a061-630c-0410-9148-cb99ea01b6c8