relax SVN archive

svn+ssh://bugman@.../svn/relax/trunk

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r20178 | bugman | 2013-06-17 15:23:40 +0200 (Mon, 17 Jun 2013) | 5 lines

The lib.io.open_write_file() function now catches file names of None and raises a RelaxError.

This is useful for the GUI if the user forgets to select a file name.
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