This function allows defining the previously fixed parameter grid_px.
The lim parameter used to define the reference Z level is also
correlated to this value.
Fixes#219
The scheme is changed from table_ovN to _vovw_N_table for
lower collision probability.
Also future naming changes will be easier by using the functions
_CDB_OverviewTableDiscriminator, _CDB_OverviewTableName,
_CDB_IsOverviewTableOf, etc.