For qt5.2 on osx, the qcocoa plugin is mandatory. However, it fails to load
when qt.conf specifies the "plugin" path instead of the expected "Plugin". This
is in line with the documentation:
https://qt-project.org/doc/qt-5.0/qtdoc/qt-conf.html
I'm not sure how the plugins were loading before, unless the case-sensitivity
for OSX is new.
Use 'osascript' to run AppleScript, instead of using (broken-in-10.8)
python appscript package.
And added support for code-signing the .app bundle, to make OSX's
GateKeeper happy.
* My patch for miniupnpc has made it into the latest MacPorts release: https://trac.macports.org/ticket/31354
* Documentation has been changed appropriately
* New pure-Python macdeployqt; leverages all problems with the stock macdeployqt