Server-level partitioning, ALTER TABLE

Added:

• Server-level partitioning [#77]:
  • one AS OF NOW, multiple VERSIONING partitions;
  • rotation of VERSIONING partitions by record count, time period;
  • rotation is multi-threaded;
  • conventional subpartitions as bottom level for versioned partitions;
  • DEFAULT keyword selects first VERSIONING partition;
  • ALTER TABLE ADD/DROP partition;
  • REBUILD PARTITION basic operation.
• ALTER TABLE basic support [#57].

Fixed:

• do not update VTQ on optimized update [#80];
• IB: SIGABRT on versioned INSERT with binlog ON [#79];
• misc shortcoming fixes.