Valgrind-detected bugs fixed

Hi  Edward,

two bugs detected by Valgrind are now fixed (commits 7e5b90a79a/4b6881417b and 09d9ff1632). Various code and documentation cleanups are also included in this pull request.

I have updated the B-Method Wikipedia page to reflect the current status of the B-Toolkit (http://en.wikipedia.org/wiki/B-Method#B-Toolkit): "The B Toolkit source code is now available[5] but is not actively maintained."

I have looked at the inconsistencies in the B-Toolkit GUI when compiled with openmotif and lesstif2. It seems that the lesstif2 is to blame, so for now I will ignore this issue.

Regards,
Piotr