Code reviewed to meet coding standards.
Removed unnecessary code
Fixed bugs due to upgrade from D6 (API changes, blocks and permissions).
Renamed some functions to avoid conflicts with D7 hooks (checked with Coder).
Fixed bug on paypernode_get_types: this function does not filter correctly allowed node types in pay per node system.
Issue #1250736 by guillaumev: fixed paypernode_user_update conflicts with hook_user_update.
Fixed problem with default values of radio buttons on admin form for bulk assignment.
Fixed bug on pay per node administration overview page (no results displayed).