World friendlier printable invoices

[Bryan Cebuliak]

Dear Derek,
OK. I tried to crash the program as I previously described using the
2.2.1 latest stable gnucash for Debian Sid.  Plus, I tried with an
open invoice. IT WILL NOT CRASH. Maybe I fixed the problem by properly
localising the Total ex Tax code with those mystery underscore
thingies. Maybe it is a problem specific to the 2.0 branch. Dunno.
So, unless someone else would like to test it first, can you load the
new code into trunk?
This will do me until some deus ex machina gives us HTML templates for
printable invoices.

Best regards to all,
Your bleeding user,
Bryan Cebuliak
Brisbane Oz