Merge pull request #23 from DougBurke/patch

BUGFIX: crash rendering a StackedLayoutLR with legends
Chart and Chart-diagrams build fine with lens-4.0.*
update Chart-diagram to work with diagrams-lib-1.1
Merge pull request #25 from byorgey/master

Updates to allow Chart-diagrams to build with latest diagrams release
Merge pull request #24 from DougBurke/patch

Added tests of StackedLayoutLR items (pull request #23)
Additional version constraints for package consistency
The test reference images are out of date, and depend on external
libraries (eg cairo and diagrams) for pixel accuracy. So, I've
removed them - the existing harnesses can be used to generate a
set of test images as required.
Merge remote-tracking branch 'origin/master' into patch
Avoid warnings with lens-4.0

This change will cause warnings when compiled with lens<4; I did not feel it was worthwhile using CPP to avoid this