import signal validity from openDrive (trac #2366)

[behrisch]

this used to differentiate signals for different directions of traffic (from the same edge or lane)

Migrated from http://sumo.dlr.de/ticket/2366

{
    "status": "new", 
    "changetime": "2016-06-02T08:26:17Z", 
    "description": "this used to differentiate signals for different directions of traffic (from the same edge or lane)", 
    "reporter": "namdre", 
    "cc": "", 
    "resolution": "", 
    "_ts": "1464855977491194", 
    "component": "net building (NETGEN, NETCONVERT)", 
    "summary": "import signal validity from openDrive", 
    "priority": "major", 
    "keywords": "", 
    "time": "2016-06-02T08:26:17Z", 
    "milestone": "1.0.0", 
    "owner": "", 
    "type": "enhancement"
}