Currency switching inconsistency

Hey,

currency switching support is used inconsistently in current plugin implementation – in /includes/class-wc-checkout-fees.php at the line number 585 ‘wc_aelia_cs_convert’ filter is being called to recalculate fixed fee, but immediately afterwards it is being compared to $min_fee and $max_fee, which are not currency aware and this is wrong.

At least $min_fee, $max_fee, $min_cart_amount and $max_cart_amount should be filtered and currency aware, too.