New support for ignoring blobs during scans. We now seek past them if we determine that they are of no use to us. This is a big save in tables with blobs. Far less memory overhead and the seek is quite a bit faster. 


mysql-test/r/archive.result:
  New results
mysql-test/t/archive.test:
  More tests for indexes and new tests for being selective on selects.
sql/ha_archive.cc:
  We now look and see if blobs are needed, and if they are not, we seek past them.