Metadata for geometric fields was not being properly stored by
the slave in its the table definition. This happened because
MYSQL_TYPE_GEOMETRY was not included in the 'switch... case' that
handles field metadata according to the field type. Therefore, it
would default to 0, leading to always have a mismatch between
master's field and slave fields'. 

We fix this by deploying the missing 'case MYSQL_TYPE_GEOMETRY:'.

mysql-test/extra/rpl_tests/type_conversions.test:
  Added some tests for blob fields and also the particular
  case for replicating from/into BLOB into/from GEOMETRY.
sql/field.h:
  As requested by Mats, reverted function added by him in
  changeset:
  http://lists.mysql.com/commits/95313