mysql-test/r/partition.result:
  Added testcase for BUG#15819
mysql-test/t/partition.test:
  Added testcase for BUG#15819
sql/item.h:
  WL#2985 "Partition pruning", postreview fixes: better comments
sql/item_timefunc.cc:
  WL#2985 "Partition pruning", postreview fixes: better comments
sql/opt_range.cc:
  WL#2985 "Partition pruning", postreview fixes: 
  - better comments, local function renames
  - Made SEL_ARG::is_singlepoint() to correctly handle NULL edge values.
  - fix uninitialized variable access: s/res |=/res =/
sql/sql_class.cc:
  WL#2985 "Partition pruning", postreview fixes: 
  Set correct max. length of "partitions" column in EXPLAIN output
sql/sql_lex.h:
  WL#2985 "Partition pruning", postreview fixes: better comments
sql/sql_partition.cc:
  WL#2985 "Partition pruning", postreview fixes: better comments