#92 use parent txn in ::delete_or_rename_table.  this removes error messages when running dict_leak_3518 test

#99 reduce analyze time to 5 seconds (from 60 seconds). this will probably allow > 1M rows to be in the cardinality computation

function if we are doing comparisons in the fractal tree, so that case-insensitivities
get resolved. Comparisons done inside the handlerton are unaffected.

closes #66, have may_table_be_empty call use the same transaction that opens and possibly creates the table, otherwise it may block behind that transaction's lock tree locks