Add Printer Device Class source files to the Atmel Studio integration XML.

git-svn-id: http://lufa-lib.googlecode.com/svn@2757 d5102386-fcda-11dd-9fdb-3debd5008f28
Minor documentation improvements.

git-svn-id: http://lufa-lib.googlecode.com/svn@2758 d5102386-fcda-11dd-9fdb-3debd5008f28
LUFA-IAR-Port: Merge in latest trunk.

git-svn-id: http://lufa-lib.googlecode.com/svn@2759 d5102386-fcda-11dd-9fdb-3debd5008f28
XMEGA-Demo-Ports: Merge in latest trunk.

git-svn-id: http://lufa-lib.googlecode.com/svn@2760 d5102386-fcda-11dd-9fdb-3debd5008f28
XMEGA-Demo-Ports: Port the DualVirtualSerial demo to the XMEGA architecture.

git-svn-id: http://lufa-lib.googlecode.com/svn@2761 d5102386-fcda-11dd-9fdb-3debd5008f28