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ARROW-4824: [Python] Fix error checking in read_csv()

Raise a TypeError when a text file is given to read_csv(), as only binary files are allowed.

Also fix a systemic issue where Python exceptions could be swallowed by C++ destructors that could call back into Python and clear the current error status.  The solution is to define a "safe" facility to call into Python code from C++ without clobbering the current error status.

Author: Antoine Pitrou <antoine@python.org>

Closes #4183 from pitrou/ARROW-4824-read-csv-error-message and squashes the following commits:

ed3f931f <Antoine Pitrou> ARROW-4824:  Fix error checking in read_csv()