BUG: prevent double plot in Series.hist
DOC: expand the documentation on the xs method
Merge pull request #4921 from cpcloud/mi-doc-blurb

DOC: expand the documentation on the xs method
Merge pull request #4113 from cpcloud/double-fig-series-hist-by-fix

BUG: make sure fig is not doubled when passing by to series.hist
DOC: show disallowed/allowed eval syntax
Merge pull request #4922 from cpcloud/eval-syntax-docs

DOC: show disallowed eval syntax