TST: unless a file is pure ascii, you must specify an encoding
TST: remove fmt.test_to_string_force_unicode

I think this is the wrong behaviour, and it breaks some
future unicode fixes. the constructor should  should complain
that no encoding was specified when the input is not ascii.
CLN: Move _is_sequence() from pd.frame to pd.common, with other is_*
TST: add test for _is_sequence()
ENH: rework console encoding detection in fmt.print_config
ENH: Add helpers to pd.common: pprint_thing/_encoded(),console_encode()
TST: add test_pprint_thing()
TST: Series repr fails when name is tuple holding non string-type #2051
ENH: SeriesFormatter footer repr now uses pprint_thing()

fixes #2051
ENH: explicitly encode retval of SeriesFormatter.to_string() with console_encode()
ENH: Index summary() and format() now delegate to pprint_thing()
ENH: tseries.Index.summary() now delegates to pprint_thing()
BUG: TextReader._explicit_index_names() should allow for unicode index_name
BUG: parsers._concat_date_cols should accept unicode
TST: test dataframe to_csv() with unicode index and columns
TST: test series to_csv() with unicode index
BUG: csvwriter writerow() now delegates to pprint_thing() for non-text objects
TST: add test for UnicodeWriter with csv.QUOTE_NONNUMERIC
ENH: add is_number() helper to pd.core.common
ENH: UnicodeWriter (CSV) now supports quoting=csv.QUOTE_NONNUMERIC