Merge pull request #1306 from eka7a/v1.5.6.2

Update version number
Fixed issues with PayPal Express checkout when using the PayPal guest payment (not registering for a PayPal account).
Added checks for address ID and if the account is logged.
Error handling added if no shipping option is found for weight based.
Fix for from and reply-to mail headers.

ref: https://github.com/opencart-ce/opencart-ce/commit/d0cc0e553099aa6f0a6f1f78599f9db650d1727d
Klarna Account gateway minimum amount update.
Wrapped PayPal express logging actions in config check to see if debugging is enabled.
Added PayPal Express fix when getting the "The totals of the cart item amounts do not match order amounts".
Updated Klarna account minimum amount for Germany to 6.95
Fixed PayPal Express state issue changing variable from PAYMENTREQUEST_0_SHIPTOCOUNTRYCODE to PAYMENTREQUEST_0_SHIPTOSTATE
Moved Daniels changes from 1.5.6.1 for the utf8 helper file.
Cookies changed to HttpOnly.
Added check for iconv and mbstring during install. Logic checks for iconv function exists first, if it does then it will not check for mbstring as only 1 is needed.

If neither are available then it will prompt for user to enable mbstring. This is only based on the assumption mbstring is better/quicker and should also be easier to enable in php by a user.
fix $length default in utf8_substr functions, set iconv internal_encoding

1) fixes utf8_substr so that it doesn't return empty strings when there is no length specified
2) set iconv internal_encoding when using iconv
3) removed explicit set of encoding on mb_strpos because already set by mb_internal encoding
Merge pull request #1313 from joshhartman/patch-1

fix $length default in utf8_substr functions, set iconv internal encoding
Added fix for PayPal express to allow for download only items and PayPal guess checkout. Guest checkout with no shipping option will not return any address data for the checkout so exceptions for no payment address data has been handled.
Added latest UTF8 helper file.
Updated PayPal express SQL qry when it searches for a matching zone based on the PayPal state data. Now searches for code or name in the database.
Re-added changes to payment/pp_express.php before download product only patch was added.