make notepadqq depend on 'libqt5svg5 (>= 5.2.1)'

Otherwise the app's icon isn't displayed in the taskbar and the 'About' window.
${shlibs:Depends} or ${misc:Depends} don't add it automatically to the dependencies.
Merge pull request #30 from darealshinji/patch-1

make notepadqq depend on 'libqt5svg5 (>= 5.2.1)'