irstv/H2GIS — pull request #327 by agouge (2014-05-23 19:19:13+00:00)
Title: Add ST_ConnectedComponents

`ST_ConnectedComponents` calculates the connected components (for undirected
graphs) or strongly connected components (for directed graphs) of a graph. It
produces two tables (nodes and edges) containing a node or edge id and a
connected component id. Signature:
```mysql
ST_ConnectedComponents('input_edges', 'o[ - eo]')`
```

where
* `input_edges` = Edges table produced by `ST_Graph` from table `input`
* `o` = Global orientation (directed, reversed or undirected)
* `eo` = Edge orientation (1 = directed, -1 = reversed, 0 = undirected).