Changed my_error() to print error messages, which come from
arbitrary registered ranges of error messages. Messages can
be unregistered (and should be at end of the program).
Added registration of handler error messages.
Added a new mi_print_error() macro and a new
mi_report_error() function, which supply error
messages with a table name.
Added calls to mi_print_error() or mi_report_error()
at all places in MyISAM, where table corruption is detected.
Fixes for embedded server
Made key_cache more configurable
Fixed that one can change key blocksize in MyISAM
A lot of optimizations to make MyISAM slightly faster
Added preliminary handling of symlinks in MyISAM.
When using myisamchk to check tables with --force, don't repair
tables that are marked as 'not closed' if they are ok.
Change fn_format() to use my_real_path and my_symlink
