BUG: to_timedelta of a scalar returns a scalar, closes #5410.
Merge pull request #5415 from danielballan/to-timedelta-scalar

BUG: to_timedelta of a scalar returns a scalar, closes #5410.
BUG/TST: bug in the test apparatus when dtypes are equal in a Series but the
         values are not equal
Merge pull request #5434 from jreback/test_fix

BUG/TST: bug in the test apparatus when dtypes are equal in a Series but the values are not equal
ENH: Add mode method to Series and DataFrame

Abstract building up the tables with counts so value_count and mode can
share. Aww! DOC: Add documentation about mode()