esql_model_table: several things:

database is not property any more;
added children_load;
added slice_get;
added children_count_get.

For children load we could in the end make use of another eo class, like esql_model_item(?) representing coordinate row:column:value,
I'll keep this possibility in mind in case we decide it is a better approach than to reutilize esql_model_table embedded with row:column:value
in itself...