BUG: error in Float64Index with contains and non-float (GH7025)
Merge pull request #7026 from jreback/float_ni

BUG: error in Float64Index with contains and non-float (GH7025)
ENH: Extends the number of Periods supported by allowing for Python defined Periods. Periods now hold reference to Offset rather than just freqstr (GH5148).
API: inferred_freq is a DateOffset subclass rather than a string. (GH5082)
removed freq_obj and changed api for freq
fix issues with freq change