Allow mixed LINESTRINGS,MULTILINESTRINGS ST_Graph
Fix OSGi test
Merge pull request #337 from agouge/st-graph-type-check

Allow mixed LINESTRINGS,MULTILINESTRINGS ST_Graph
Before, `ST_Graph` raised an exception if the input table contained both
`LINESTRINGS` and `MULTILINESTRINGS`. Now we allow for this possibility.

If we find a Geometry other than `LINESTRING` or `MULTILINESTRING`, we raise an
exception with the type.