Created attachment 717109 [details]
add support to unset options, add CURLOPT_RANGE to the list.

Description of problem:

There's no way to remove the HTTP ranges, once set.  Recycling a curl object or calling .reset() method is an option, however pycurl should offer the complete feature set of libcurl, which supports that:  "Pass a NULL to this option to disable the use of ranges."

However, setopt(pycurl.RANGE, None) raises a TypeError exception.  The "unset" code path could be uncommented, and CURLOPT_RANGE added to the list of simple string options.

How reproducible:

Alwasy.

Steps to Reproduce:

>>> import pycurl
>>> c = pycurl.Curl()
>>> c.setopt(pycurl.RANGE, '0-10')
>>> c.setopt(pycurl.RANGE, None)
  
Actual results:

TypeError: invalid arguments to setopt

Expected results:

No error.

Additional info: