1.4.0rc0

First release in the 1.4.x series.
This release includes enhancements and bug-fixes towards the release of the first
beta version of *dMRIPrep*.
It also contains new features that are necessary for the API overhaul that has
happened within the new *SDCFlows 2.x* series.
Finally other *NiPreps* will also have a first release with specific support for
them: *NiRodents* and *NiBabies* (and their corresponding *fMRIPrep* extensions).

A list of prominent changes follows:

* FIX: Allow omission of ``<res>`` for template normalization (#582)
* FIX: Include ``_T2starw`` ``_MTw`` and ``_TSE``-suffixes in ``build_path`` options (#584)
* FIX: ``DerivativesDataSink`` warning when it has multiple source files (#573)
* ENH: Upstream *fMRIPrep*'s ``init_bbreg_wf`` to integrate it in *dMRIPrep* (#586)
* MAINT: CircleCI housekeeping (#580)