Partition pruning, History truncation

Added:

• Partition pruning [#97]:
  • based on RANGE pruning by COLUMNS (sys_trx_end) condition;
  • removed DEFAULT; AS OF NOW is always last; current VERSIONING as last non-empty (or first empty);
  • ALTER TABLE ADD PARTITION adds before AS OF NOW partition;
  • Min/Max partition stats are multi-threaded.
• History truncation [#96, #111]:
  • FOR SYSTEM_TIME clause for TRUNCATE TABLE;
  • FOR SYSTEM_TIME BEFORE syntax extension.
• FOR SYSTEM_TIME is now table-local or query-global [#116]:
  • QUERY keyword makes it query-global.

Fixed:

• Row-based replication [#94, #107];
• FK cascade delete when parent versioned [#101];
• FOR SYSTEM_TIME support in VIEW expression [#99];
• Prohibit write-locking of historic rows [fixes #102];
• ALTER ADD AUTO_INCREMENT for versioned tables [#112].