- use m prefix for member variables and s prefix for class variables
- refactor QgsPostgresProvider::Conn and QgsPostgresConnection to QgsPostgresConn
- put QgsColumnTypeThread into separate file
- use QgsPostgresConn in QgsPgSourceSelect
- cleaner abort of column type thread (e.g. remove unfinished columns from
selection list)
- [API] move QgsDbTableModel as QgsPgTableModel to provider
- [FEATURE] support for arbitrary key (including non-numeric and multi column)
- [FEATURE][API] support for requesting a certain geometry type and/or srid in QgsDataSourceURI
* no more explicit filter strings
* support for empty tables without gemetry_columns entry or GEOMETRY type.
