fix: spm_realign code to handle 3d files without registering to mean
fix: spm_realign always reslices to the first volume even if register_to_mean rtm is set to True
ENH importing basic pieces at a top level
ENH adding external interface namespaces to top-level imports
fix: resolved conflict
sty: many pep8 fixes
remove deprecated stuff
Fixed tests and docs
Merge pull request #596 from mwaskom/enh/top_level_imports

Import central classes at higher levels in the package hierarchy
Merge pull request #571 from satra/fix/realign_w3dfiles

Fix/realign w3dfiles
Merge pull request #599 from chrisfilo/temp_fix/automask

Temp fix/automask
Merge remote-tracking branch 'bpinsard/spm/reslicetoref'

Conflicts:
	CHANGES
Merge branch 'master' into testing

* master:
  Fixed tests and docs
  remove deprecated stuff
  sty: many pep8 fixes
  ENH adding external interface namespaces to top-level imports
  ENH importing basic pieces at a top level
  fix: spm_realign always reslices to the first volume even if register_to_mean rtm is set to True
  fix: spm_realign code to handle 3d files without registering to mean