DOC: document read_html and to_html

remove import of read_html
DOC: fix reference to read_html
Merge pull request #3704 from cpcloud/read-write-html-docs

DOC: document read_html and to_html
API: deprecate unused DataFrame.replace arguments
DOC: clean up io docs and fix up links
Merge pull request #3720 from cpcloud/null-funcs-api-doc-generate

DOC: clean up io docs and fix up links
Merge pull request #3712 from cpcloud/deprecate-unused-replace-args

API: deprecate unused DataFrame.replace arguments
ENH/API: implemenet __nonzero__ for NDFrame

ENH/API: remove __nonzero__ in frames, use NDFrame implementation
DOC: add release notes
Merge pull request #3696 from cpcloud/nonzero-3691

ENH/API: implement __nonzero__ for NDFrame
DOC: doc building fixes
ENH: add new option syntax
Merge pull request #3677 from cpcloud/option-syntax-enh-3667

ENH: enhance set_option syntax
DOC: api.rst updates
DOC: v0.11.1 editing
DOC/BLD: fix annoying sphinx bugs
DOC: io/v0.11.1 changes
DOC: older version of bs4 for 64bit as well
Merge pull request #3724 from changhiskhan/PR_bs4-doc

DOC: older version of bs4 for 64bit as well
DOC: v0.11.1 cross-links to other parts of the docs