Merged all ddl_logging code.
Merged sql_partition.cc
innodb_mysql_lock2.test and partition_cache.test now works.
Changed interface to strconvert() to make it easier to use with not \0 terminated strings.

sql/sql_partition.cc:
  Full merge with 5.6
sql/sql_table.cc:
  Merged all ddl_logging code
sql/strfunc.cc:
  Added from_length argument to strconvert() to make it possible to use without end terminated strings.
sql/strfunc.h:
  Added from_length argument to strconvert() to make it possible to use without end terminated strings.