Move oox/drawingml/*hxx internal headers to oox/inc.

Do not export LinePropertiesContext class as visible.

And move GraphicProperties to its own header.

Change-Id: I047c181e9f2adc7e59885f59663ea56c7eb898ed
bnc#591147: OOXML import: Import video file too.

Change-Id: Ie9b6c5ff866269e5d7a26d025cb1c0d884ff1134
Replace struct EmbeddedWAVAudioFile with simple string.

Change-Id: I6659b6e1be865546f380a28e4803fbe593de0803