1.6.9

* MarketPress: Beta released
* Common: Allows overriding language files by placing them into
/wp-content/languages/paymill/
* PayButton: Order Form optimized
* PayButton: Feature for price/currency format
* Shopp: Paymill as Payment Gateway wasn't recognized due to last
changes in shopplugin - fixed
* Shopp: Errors wasn't shown on checkout process - fixed
* Shopp: Compatibility with new checkout button achieved