Sav export not setting correct format for floats

[AndersFreund]

get_savwriter_float_format is not always calculating the correct length of the int part of a float.

This happens because Series.max doesn't return the numeric max when applied on a series with dtype=object.

quantipy/quantipy/core/tools/dp/spss/writer.py

Line 133 in 82ef628

w_int = len(str(df['int'].max()))

[AndersFreund]

Here my take on this #1342