Enable the "#include <QMediaMetaData>" camel-case header

Move the QMediaMetaData namespace into new files, and have sync.profile
generate the camel-case header during compilation.

For now, the new header (qmediametadata.h) is included whereever the old
one appears (qtmedianamespace.h), but an audit will be done later to
make explicit #includes only where necessary.

NOTE: Git may think that a rename has occurred.

Part of the Header Consistency Project
(http://lists.qt-project.org/pipermail/development/2012-October/007570.html)

Change-Id: I63705722a5e175628d56128888a94ae4c20879f2
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

src/multimedia/multimedia.pro

@@ -26,6 +26,7 @@ PUBLIC_HEADERS += \
     qmediabindableinterface.h \
     qmediacontrol.h \
     qmediaenumdebug.h \
+    qmediametadata.h \
     qmediaobject.h \
     qmediaservice.h \
     qmediaserviceproviderplugin.h \
@@ -36,6 +37,7 @@ PUBLIC_HEADERS += \
 SOURCES += \
     qmediabindableinterface.cpp \
     qmediacontrol.cpp \
+    qmediametadata.cpp \
     qmediaobject.cpp \
     qmediapluginloader.cpp \
     qmediaservice.cpp \