Python 3 fixes for degridding support

Bug fixes

• residual python 3 porting in degridding modes
• fixes issue with io queue shutdown for degridding modes

Hotfix for typo introduced on max-chunks

Single chunk 323 typo (#340)

* Fix #338 Fix #337

* hotfix for typo in last PR

DDFacet 0.5 support

Bug fixes for:

• supporting ddf v0.5+
• degridding bands selection in initialization of ddf predictor
• fixes for single tile debugging mode

Your degrids are Numba'd

Adds support for degridding using DDFacet machinery and replaces all Cython with Numba for +- 30% improved performance.

Final pre-numba release

Release of up-to-date functionality prior to Numba integration.

Minor py3 port errors and optional montblanc dependency

• montblanc install is now optional, use [lsm-support] when installing
• minor py3 leftovers

Reached the Python 3 era!

Enough said

To bin or not to bin - Hotfix#1

Fixes a trivial error which slipped testing.

To bin or not to bin

Addition of on-the-fly rebinning as well as some more advanced flagging options. Users are encouraged to use the version available on PyPI, which can be installed using pip. As usual, please report any new and exciting bugs.

The Enthreadening

Major revisions to kernels courtesy of @o-smirnov. Multithreading now available for when chunk sizes grow too large. As usual, please submit issues for new and exiting bugs.