Enable read_csv to interpret "Infinity", "+Infinity" and "-Infinity" as floating point values
The strings "Infinity", "+Infinity" and "-Infinity" are commonly used to represent infinite floating point values. It would be great for pandas pd.read_csv to correctly interpret these strings as infinite floating point values or to take a parameter "inf_values" analogous to "na_values" that would allow the caller to specify what they require.
