STL (slower than light) interstellar travel

**What do you want to see?**
Make the map into a GalCiv style map, with star systems "stamped out" across a huge void. If the enemy blockades a warp point, you can take the slow way around.

**How would it help players?**
More strategic options; warp point chokepoints are not so chokey.

**Alternatives**
N/A

**Screenshots and mockups**
Just play GalCiv :)

**Things to consider**
Sensors will need to be adjusted since they currently let you see anything in the star system, but there's also space outside the star systems. Maybe give them a range equal to the size of the largest star system? Or let the default sensor range be set in game setup? Maybe add SE5 style sensor range as an option?