CHT: API for filtering events

[matley]

Design and implements an API for filtering events.

Geometry input parameters should be nhlib geometry class instances https://github.com/gem/nhlib/tree/master/nhlib/geo

The following APIs should be designed and implemented:

1) Global search. Find all the events
2) Distance Search. Find all the events within a distance of (e.g. 300 km) from point (Lon, Lat)
3) Polygon Search. Find all the events that lie on the surface enclosed by a polygon (Use WKT to denote a polygon).

Each API return value should be of type sqlalchemy.orm.Query ( http://docs.sqlalchemy.org/en/latest/orm/query.html#sqlalchemy.orm.query.Query )

Each API result set can be further refined by applying one or more filters. E.g.

Event.distance_search(aPoint, aDistance).filter_by(magnitude > 5).filter_by(date < datetime.now())

Provide test cases for each API method. Some test fixtures can be found at https://bugs.launchpad.net/openquake/+bug/979915/+attachment/3053004/+files/myanmar_sample_catalogue_for_queries.csv

Some query examples are given in https://bugs.launchpad.net/openquake/+bug/979915

[Graeme Weatherill (graeme-9)]

Some test data:

i) test_query_input_catalogue.csv - Short catalogue for geometry selection tests
ii) test_geometries_2polygons_1point.txt - Description of the geometries of two polygons and one point for geographical distance testing.
iii) solution_in_polygon_results.csv - List for each measure in test_query_input_catalogue.csv indicating True or False is the measure is inside polygon 1 or 2 respectively, and the distance (in km) from the point.