DOC improve encoding docs
removing NWS from list of stock prices
MAINT remove deprecated code from CD
FIX finish deprecation of indices in CV

* default None value so explicit True/False can be detected
* remove doc for deprecated indices parameter
* indices property with DeprecationWarning

Fixes #2436.
Partially revert "MAINT remove deprecated code from CD"

This reverts commit 680234d3687c22023d99a439ee832d9d33136c9d.

The dictionary learning code seems to rely on coef_init (even
though CD docstrings say it's a no-op). I leave it to @vene and
@agramfort to sort this out further.
FIX issue #1993: passing a multilabel indicator is no more noop
TST speed up biclustering tests

They were taking 7s to run, down to 3.6s.