v5 - new major version

[enisz]

• IGDBUtils webhook support
• IGDBQueryBuilder updates:
  • building standard and multiquery query strings is now separated to their respective methods:
    • build: standard apicalypse query
    • build_multiquery: multiquery query string
• Wrapper updates:
  • synchronised API endpoints from IGDB, every available endpoint has its wrapper endpoint method counterpart
  • endpoint methods - and multiquery - now accept both an apicalypse query string or a configured IGDBQueryBuilder instance(s)
  • every endpoint method has its count counterpart. Count parameter is no longer available for the endpoint methods
  • multiple constant values are moved to a dedicated file IGDBConstants.php.