channel-main: Convert text line-endings if necessary (rhbz#752350)
channel-main: Convert text line-endings if necessary (rhbz#752350)

This implements line-ending conversion following the specification in the
commit message of spice-protocol commit 7be0e88e7e03a956b364cc847aad11b96ed4 :
vd_agent: Add caps for the agent to signal the guest line-ending (rhbz#752350)

Signed-off-by: Hans de Goede <9fa1be1a5b5729e4c6b404f34c9ce49ff4882fd8@redhat.com>

Fantu/spice-gtk,elmarco/spice-gtk,Fantu/spice-gtk,elmarco/spice-gtk,flexVDI/spice-gtk,Fantu/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,SPICE/spice-gtk,SPICE/spice-gtk,fgouget/spice-gtk,Fantu/spice-gtk,elmarco/spice-gtk,guodong/spice-gtk,flexVDI/spice-gtk,guodong/spice-gtk,SPICE/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,guodong/spice-gtk,guodong/spice-gtk,elmarco/spice-gtk,SPICE/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,fgouget/spice-gtk,fgouget/spice-gtk