Release v0.2.2

[0.2.2] [Minor] - 2021-12-07

Added

• transaction API (with transaction.h) including:
  • transaction helper types in new transaction.h including flag_t, config_t,
    status_t, and result_t (with appropriate name prefixes), as well as wfb
    (with fallback) variants where necessary
  • patomic_transaction_abort_reason helper function
  • transaction ops types in ops.h with additional ops flag_ops, special_ops,
    and raw_ops
  • transaction_t extras: recommended (recommended limits for transactions)
    and sstring (safe string operations that won't abort the transaction)
  • multiple checks for transaction implementations
• feature check API in feature_check.h
• PATOMIC_MAX_CACHE_LINE_SIZE macro in align.h
• corresponding patomic_cache_line_size function in align.h/align.c
• config macros to check for MS/GNU alignment extensions

Changed

• std implementation now checks for MS/GNU alignment extensions before
  defaulting to using sizeof in place of _Alignof