Added checking and requesting ask permission example to russian version
Added checking and requesting set status permission to english version
Added example of setting status to both english and russian versions
Added showInvite() examples to both russian and english versions
Added examples for showNotification() for both russian and english versions
Added examples of showPayment() to both russian and english versions + simple server-side confirmation. There is no server-side payment check, it is written in comments.
Added payment.php. Now payment works.
Updated comments
Added example for showPortalPayment() in both russian and english versions.
Added examples for setWindowSize() for both russian and english versions.
Now there are examples for all FAPI.UI methods
Englis version only. Now logging payment operations with error_log().
English variant of payment processing.
Added check-up for existing params product_code and amount in get request
Added russian translation of payments.php .
Fixed xml format
Improved code style
Improved code style: constants for error numbers, createXMLWithRoot function
Added signature check
Fixed bug in russian version