Better name for "Accounts" tab and "Trading Accounts" option?

[Jeff Kletsky]

I've been poking around with setting a default budget and find myself in 
qofbookslots.h which was apparently introduced for
<https://bugzilla.gnome.org/show_bug.cgi?id=537476>
which, at least as I understand it, implements "trading accounts" to 
handle multi-currency and multi-commodity transactions. I've been able 
to mainly resolve the swig-guile-gettext interactions related to getting 
the strings to translate, which I'm hoping to get in with some of the 
default-budget changes here in a couple days.

There is further discussion as well at 
<http://www.mathstat.dal.ca/~selinger/accounting/gnucash.html>

The option appears in the book-level preferences, along with the 
business-related fields. Right now, the tab is labeled "Accounts" with 
"Trading Accounts" (as the only option so far) which left me puzzled. 
Any better suggestions for these?

Now would be the time to make them, since they end up being both UI 
strings, as well as the keys for the KVP data, so, once set, shouldn't 
be changed (until there is some future support for decoupling the UI 
label from the data key).

"Multi-Currency"
"Use trading accounts"

or

"Multi-Commodity"
"Use trading accounts"

make a little more sense to me, but even "Multi-Currency" is a tad long 
(but do-able). Setting the tab label to something somewhat generic 
provides a place for future book-level preferences that are related.


Suggestions welcomed,

Jeff