Use previous Atmel Studio VSIX identifier so that it can upgrade existing installations.

git-svn-id: http://lufa-lib.googlecode.com/svn@2743 d5102386-fcda-11dd-9fdb-3debd5008f28
Fix Serial peripheral driver compile error for XMEGA devices.

git-svn-id: http://lufa-lib.googlecode.com/svn@2744 d5102386-fcda-11dd-9fdb-3debd5008f28
Minor documentation improvements.

git-svn-id: http://lufa-lib.googlecode.com/svn@2745 d5102386-fcda-11dd-9fdb-3debd5008f28
Oops - ensure the Atmel Studio extension package has the same GUID as the one used in the VSIX manifest, to prevent Studio from re-running the pre-/post-install actions every time.

git-svn-id: http://lufa-lib.googlecode.com/svn@2746 d5102386-fcda-11dd-9fdb-3debd5008f28