More locco update to make it html5 conform
QA/pagediff adopt to new version of imagemagick

The return code of compare seems to be now (how was it before?)
0 no difference in the given images
1 if the comparison is OK, but with differences
2 if there is a fatal error
Bugfix: default main language

This slipped through the commit 927bbcdb7...
Source code documentation

Add images to `tabular.lua' and add mathjax for formulae