ENH add fake root node to RST dep tree (incomplete)
Merge branch 'rst-split-feat-extraction' into rst-dep-fake-root
Merge branch 'master' into rst-dep-fake-root

Conflicts:
	educe/rst_dt/learning/base.py
FIX better and simpler fake root node
ENH para and sent for fake EDU
ENH cleaner fake root
ENH better fake root node handling
FIX space sep for pair features
FIX list comprehension instead of map
MAINT pylint n pep8
MAINT fix in docstring
MAINT s/dif/diff
FIX mandatory fake root, cleaner padding
Merge pull request #19 from moreymat/rst-dep-fake-root

Add fake root to RST-dep tree