Update progressbar usage

setup.py now requires progressbar2.
Convert some usages of progressbar to use sapphire.utils.pbar.
Remove some if statements and use the `show` option of pbar.
Fix missing import of progressbar in coincidences.
Use from..import.. of progressbar to make some usages one line instead
of 4.
Should be backwards compatible with progressbar 2.3, but easier to
install.
Fixes #33.