TST/FIX ensure correct ducktyping for metaestimators
TST extend ducktype testing to handle #2853 case
FIX ducktyping for meta-estimators
TST more rigorous testing of delegation
remove _iff_attr_has_method function
don't give names to decorators
make attribute decriptor have the right docstring.
add regression test for docstring delegation
fix docstrings in sphinx
rename decorator
Fix typos, no shortenings in name, simplify example.
ENH vectorize DBSCAN implementation
ENH sparse support in DBSCAN
ENH support weighted samples in DBSCAN
FIX DBSCAN.fit_predict now also supports sample_weight
DOC/COSMIT clean up according to review
Merge pull request #3994 from jnothman/vec_dbscan

[MRG+1] DBSCAN: faster, weighted samples, and sparse input
TST add tests for nd grid-search can train_test_split
MAINT dev version to follow PEP440
FIX correct name due to rebase error