Energy conservation failing on triangular example but all tests passing

[edmundsj]

Last working commit on develop branch was 089e52b.

Need to find out what caused it to break and why the integration tests didn't catch it. If I haven't yet added full integration tests for triangular photonic crystal, that needs to be done.

Bizarrely, manually resetting all of my main source files to that commit does not appear to fix the problem, but resetting everything in the repository does.

[edmundsj]

This is now fixed on the develop branch by reverting to a previous commit, and unit tests have been added for all examples to ensure it does not recur. 22383ff