Tl windows deploy fix

Dear Joker developers,

This pull request tries to improve how Joker is deployed under Windows. It uses windeployqt, a tool provided with Qt (starting from 5.2), whose purpose is to copy all the necessary dlls for a Qt program. Using this tool helps deploying the proper dlls, given that Qt plugin system can be quite complicated and that some dll names may change with Qt versions.

The Innosetup script is modified accordingly. Another direst benefit of these commits is that Joker executable can be successfully started by double-clicking on it in the explorer.