Reorganize the .qrc file(s)

Split the single .qrc file up into audio, graphics, qml and
translations. That increases build speed after changes just in
.qml files.

List each file separately in each .qrc instead of the semi-
supported folder name definition. That improves support by Qt
Creator's .qrc file upport in the project tree. Also, it allows
to use the Qt Quick Compiler.