Lego Duplo Train Bridge

Liked the duplo bridge from [pjotrx](https://www.thingiverse.com/thing:122268). From my point of view it has only one flaw, when printed with only one middle section, it's not high enough to pass a train underneath.

Although not really planned, just remodeled the whole bridge again:
* In the middle, the bridge should be 6 bricks high, so the train fits underneath.
* Using pjotrx straight element section (8 nopes length, 3 bricks high), enabling endless high bridges, nice :)
* Using pjotrx interfaces, so it's fully compatible.
* Straight sections with only one pillar.
* Also the old duplo cars fits the track. (Not the case with the original duplo bridge version.)
* Longer initial ramp, so no problems with specific train/wagons combinations. (As recommended by [basestring](https://www.thingiverse.com/thing:2546186))
* Total bridge length is 7 standard straight track lengths.
* Added some additional pillars (2,3,4,5 or 6 bricks height).

Testing:
Also experiment a little wit