TST: Tests and fix for unhandled data types in Excel writers.

Added tests and a fix for unhandled numpy data types in the
Excel writers. Issue #3122.
BUG: apply Timestamp to resultant datetimes when operating on offsets
fix replacement key for deprecated option `display.height`

replacement key for deprecated option `display.height` was set to `display.height` itself. I believe it should be `display.max_rows` instead.

This avoid a weird message in `describe_option()` :

    display.height: [default: 60] [currently: 60]
    : int
            Deprecated.
	    (Deprecated, use `display.height` instead.)
Merge pull request #5197 from jreback/to_datetime

BUG: Bug in to_datetime with a format and coerce=True not raising (GH5195)
inlined some functions and avoid repeated conversion factor calculation when using period_asfreq_arr in period.c
BUG/TST: Test filter corner cases, and treat NaN as False.
DOC: Note -> Notes (numpydoc docstring section)
DOC: make api docs reflect api usage (#4539)
BUG: Bug in loc setting with multiple indexers and a rhs of a Series that needs
     broadcasting (GH5206)
Merge pull request #5210 from jreback/loc_index

BUG: Bug in loc setting with multiple indexers and a rhs of a Series that needs broadcasting (GH5206)
Merge branch 'c_inline' of https://github.com/wuan/pandas into wuan-c_inline
Merge pull request #5096 from danielballan/filter-len-test

TST: Groupby filter tests involved len, closing #4447
CLN/BUG: Better validation of levels/labels/names
Merge pull request #5122 from jmcnamara/tst_excel_types

TST: Tests and fix for unhandled data types in Excel writers.
Merge pull request #5209 from jtratner/validate-everything-on-mi

CLN/BUG: Better validation of levels/labels/names
Merge pull request #5181 from pierre-haessig/patch-1

fix replacement key for deprecated option `display.height`
Merge pull request #5207 from jorisvandenbossche/docs-note

DOC: Note -> Notes (numpydoc docstring section)
BUG/CLN: Clear _tuples on setting MI levels/labels
Merge pull request #5215 from jtratner/mi-clear-tuples-on-mutate

BUG/CLN: Clear _tuples on setting MI levels/labels
CLN/ENH: Stop instantiating all offsets on load.

Use a more flexible lookup based on prefix then delegate creation to
class' `from_name()` method. Totally get rid of hasOffsetName (not necessary).
Finally, make some inheriting go on to simplify things.