sc 0.50.2

• Unified transaction syntax:
  • Better compilation error messages for malformed transactions;
  • Deprecated methods async_call and async_call_promises, which are kept for backwards compatibility, but causing confusion among developers;
  • Contract upgrade available in tests.
• sc-meta proxy compare option, which checks that proxies are up to date. Useful for CI.
• TypeAbi - removed Unmanaged associated type trait bounds, and implemented it for more types.
• Removed jitter from interactor transaction fetch.
• Fixed an issue in the snippets generator.