debugging wierd dcd issue
(1) DCD seek now works better. Fixes bug on travis. (2) travis runs with conda python instead of apt + wheels (3) Remove cython autogenerated c files from repository.
make cython manditory
Simplify
Merge pull request #368 from rmcgibbo/debuging-the-wierd-dcd-failure

DCD Bugfix on travis + switch to conda python for testing on travis + remove autogenerated cython files from repo