wq.core 1.2 beta

wq.core 1.2.0b1 is the beta of the upcoming 1.2 version of wq.core. The functionality is the same, with a few cosmetic improvements:

• use setuptools_scm & markdown readme (1a4cfab)
• use safe_load() to avoid YAML warning (ce2dca7)
• don't check if wq.io is installed - it was renamed to IterTable (509c90f)