* Advanced trading fixes/modifcations
This adds combine currency option to the Advanced trading screen since
@Airwaves man noticed it didn't have a way of doing it.
Updated stringtables with correct "paid" spelling and differing text for
buying/selling.
This also addds proper currency checking/reporting for the log system
that has been introduced, it's untidy but it works, instead of getting
"user bought x for 1000 currency" in a non coins server, it will convert
it to the proper 1 brief 5 10oz gold etc system (uses a new function
z_calcDefaultCurrencyNoImg)
This also adds a check to see if the buy list is empty (as per the
selling list) and returns text to the user informing them.
Re-arranged buy and sell so buy is on top of sell, it's a bit easier to
read then.
* Advanced trading logging change
This was missing from my previous commit, this changes the
server_tradeobject to check if it's being passed a number (single
currency) or text (my logging currency changes)
* Advanced trading rework
Fixes all problems @ebaydayz
Fixes currency display name and picture not showing when looking at
backpack item info.
Also fixed localized string for weps and mags order reversed in item
info for backpacks and vehicles.
