Log Message:
Added a MESSAGE file that is shared with both lyx-qt and lyx-xforms.
And bumped PKGREVISIONs.

This MESSAGE suggests that the user run's LyX's reconfigure option
when upgrading or adding other packages.

The MESSAGE also lists several packages that can extend LyX.
(Later, when wip/sgmltools-lite and wip/html2latex are added to
pkgsrc these should be added to the list.)