* remove phase one/two distinction and hdbquery typeclass
* move extensions to default-extensions
* switch to LazyTx which only acquires a connection if needed
* move defns from TH module into Ops module
* remove tojson orphan instance for http exception
* remove orphan instance for dmlp1
* getTopLevelNodes will not throw any exceptions
* allow ordering using columns from object relationships, close#463
* validate table fields in nested insert
* add tests
* add docs
* change 'table_order_by' type from enums to ordered map
* remove unwanted code from 'Schema.hs' file
* 'AnnGObject' is not list of field name and value tuple
* update docs for new order_by type
* use 'InsOrdHashMap' for 'AnnGObj'
* handle empty fields in order_by
* remove '_' prefixes for asc/desc
* fix the changed order_by syntax across the repo
* support for count and aggregations on columns, close#786
* support explain query for aggregations
* '<arr-rel>_agg' in '<table>' type, fix order by for aggregations
* add 'allow_aggregations' key in select permissions
* Add checkbox to toggle count and aggregations on columns on select permission
* align aggregation checkbox with columns div
* improve readability of the generated sql
* alias is needed at the top level aggregation
* throw internal errors for unexpected fields
* rename SelFld to more readable TableAggFld
* rename agg to aggregate
