Add Steam Card Exchange links on store page. Adds #433
Add Steam Card Exchange option on options page.
Fix Steam Card Exchange property names
PREP: 6.7
FIX: SteamCardExchange links
FIX: language cookie check

It seems that a recent change made by Valve makes it so that your
language is tied to your account which means Enhanced Steam can no
longer access the language by the cookie data.  This is a temporary
workaround until this feature goes live.
ADD: Function for extracting currency symbol

This should make future updates easier when new currencies go live
ADD: Basic support for Malaysian Ringgit
ADD: Basic support for Norwegian Krone
ADD: Basic support for Indonesian Rupiah
ADD: Basic support for Philippine Peso
ADD: Basic support for Singapore Dollar
ADD: Basic support for Thai Baht
ADD: Basic support for Vietnamese Dong
ADD: Basic support for South Korean Won
ADD: Basic support for Turkish Lira
ADD: Basic support for Ukrainian Hryvnia
ADD: Basic support for MXN and CAD
ADD: Basic support for Australian Dollar
ADD: Basic support for New Zealand Dollar