Fix alert issues

NSBeginAlertSheet has a built-in "printf" string formatter. If the final parameter -- the alert message -- calls "stringWithFormat", the effect is to calculate the _format_string_, and not the message itself. In SDK 10.8, the compiler warns:

	Format string is not a string literal (potentially insecure)

This patch resolves these issues by unwinding the message paramenter to NSBeginAlertSheet, adding a simple string literal @"%@" where necessary.