V. 1.7.0

This update further focuses on speeding up the workflow and fixing bugs.

Changelog:
- Added automatically generate main roads for intersection which connectes the non-connected lanes of roads. For example if two roads have a sidewalk that consists of 3 lanes then those will connected to continue through the intersection. See the picture above for an example. This should be a huge time saver when it comes to creating intersections!
- Added possibility to add a custom physics material to roads and intersections (defined per lane/intersection main road for more cusomization)
- Added possibility to change y-offset for intersection main roads
- Made road preset values more accurate, y offset 0.5 instead of 0.500768 for example, this was due to it being pratically inpossible to select exact values in the curve editor.
- Fixed end index for intersection connections labled start index in the editor
- Multiple bug fixes regarding intersection main roads