use explicit imports
clean up math module a bit
clean up some more tests
latexarray.to_pdf was overwriting the decimals argument
make pylint happier
more pep8 goodness
add a changelog
can't have a comment at the top of the file...
Merge pull request #53 from Autoplectic/changelog

Add a nicely formatted changelog to dit.
Merge branch 'master' of github.com:dit/dit
Comment/docstring updates.