Reports and the root account

[Phil Longstaff]

While doing some testing on the sql backend, I noticed that when I run a 
report (e.g. Balance Sheet), the report system attempts to query all 
transactions for the root account.  The sql backend tries to do a 
xaccAccountLookup() on the guid in the qofQuery, and fails when it returns 
NULL.

I could detect this and fail more gracefully i.e. ignore this account, but I 
think it should be handled in the report system.  I don't plan to address this 
right now, but can log this in bugzilla if no one else wants to look at it in 
the near future.

Phil