Alter VSIX build script to verify all referenced filenames in all modules and projects, rather than just the core modules. Fix discovered errors in the project XML files.

git-svn-id: http://lufa-lib.googlecode.com/svn/trunk@2555 d5102386-fcda-11dd-9fdb-3debd5008f28
Check referenced distribute build files in the project XML files, as well as C source and header files.

git-svn-id: http://lufa-lib.googlecode.com/svn/trunk@2556 d5102386-fcda-11dd-9fdb-3debd5008f28
Ensure the demo and project main text files are distributed in Atmel Studio projects.

git-svn-id: http://lufa-lib.googlecode.com/svn/trunk@2557 d5102386-fcda-11dd-9fdb-3debd5008f28
Add Atmel Studio keywords to all project XML files.

git-svn-id: http://lufa-lib.googlecode.com/svn/trunk@2558 d5102386-fcda-11dd-9fdb-3debd5008f28