Comment in tests for WKBElement bind value
InsertionTest class renamed to InsertionORMTest
Add test_WKBElement

This test demonstrates that this works:

obj.geom = WKBElement(...)
session.add(obj)

It works because, in that case, the WKBElement object is not a bind value. It is function call (ST_GeomFromWKB).
Use type_coerce in functional tests
Move test to proper test file
Doc changes for EWKT support