Final patch
-----------

This WL is about using this bitmap in all parts of the partition handler.
Thus for:
rnd_init/rnd_next
index_init/index_next and all other variants of index scans
read_range_... the various range scans implemented in the partition handler.

Also use those bitmaps in the various other calls that currently loop over all
partitions.




mysql-test/r/partition_pruning.result:
  WL# 2986
  
  New results reflecting bitmap being used to determine if a partition is to be
  included
mysql-test/t/partition_pruning.test:
  WL# 2986
  
  New tests to show bitmap being used in ha_partition
sql/ha_partition.cc:
  WL# 2986
  
  Used work from 2682 and removed the partition select code.
      
  Added do {} while loop to any iteration over partitions to now utilise 
  m_part_info->used_partitions bitmap to determine if a partition should be
  used.
sql/ha_partition.h:
  WL# 2986
  
  Removed unused member
sql/handler.h:
  WL# 2986
  
  Removed unused member
sql/opt_range.cc:
  WL# 2986
  
  Added bitmap_clear_all to clear bitmap prior to pruning
  DBUG code for testing
sql/sql_partition.cc:
  WL# 2986
  
  Changed < to <=, which fixes the problem with edge cases going awry.