feature request: convert old style signals to new style signals ONLY

[thorade]

pyQt4 supports old style signals and new style signals, pyQt5 supports new stylesignals only, according to http://pyqt.sourceforge.net/Docs/PyQt5/pyqt4_differences.html

This script converts from old to new style, but it also does a lot of other things. Would it be possible to do the conversion in two steps, first convert only the signals to the new style, resulting in code that still works in pyQt4 (but not yet in pyQt5)? Then, the second step would change the imports, thus breaking pyQt4 support.