import modules as it described in PEP 328
pybeam.beam_file: use open() instead of removed file()
test.eetf_construct: fix python3 syntax errors
pybeam.eetf_construct: fix for python3 (sort strings out of binaries)
pybeam.beam_construct: fix for python3 (sort strings out of binaries)
Simplify unittest usage
Add python 3 to .travis.yml
Improvements in test
Add unittest for beam_construct.chunk_litt
pybeam.beam_construct: implement chunk_litt using codecs (python3 support)
pybeam.beam_file: fix for python3 (sort strings out of binaries)
Add note about python3 to README.md