Ability to log errors to a file object

[martinohanlon]

Rather than raised errors, the option should exist to log errors to an open file object, including stderr.

Based on requests in #7 from @kiwi0fruit

[martinohanlon]

If ShortCutter is not in silent mode #11 errors will be raised.

ShortCutter should accept an error_file IO object on the constructor (defaulted to None) which when set causes errors to also be written to the error_file and not raised as exceptions.

[kiwi0fruit]

I suggest explicit skip_errors=True/False and error_log=None/sys.stderr/io.StringIO() where None means silent mode. This way skipping errors cannot be activated in two different ways (as you suggest).

[martinohanlon]

How do you see skip_error being different to silent'? silent seems more prescriptive than skip_errors - the error cant be skipped, they are simply not reported.

if error_log=None means silent, how would a user get python exceptions raised?

[kiwi0fruit]

if error_log=None means silent, how would a user get python exceptions raised?

skip_errors=False raises exceptions. I want to say that an explicit switch for raising/not raising mode is better. How to call it? raise_errors=True/False?