Create button for add/select new road before/after roadpoint

[TheDuckCow]

As a part of this macro-scopic issue, we want to be able to easily add add new RoadPoints for easy creation of road networks. Right now, we have to fiddle with updating pre/post roadpoints in a chain, and manually retrigger refreshing of the layouts as roadpoints are duplicated

Requirements for this task:

• Add 4 more buttons to the RoadPoint panel (Note: Already being done by this PR), 2 for add new [next/prior] and 2 for select [next/prior]
• When clicked, automatically add a new RoadPoint (this should be a new instance)
• When the new roadpoint is added, it should automatically be automatically set up to have the match lanes and other settings: Magnitude, number of lanes, auto lanes bool, lane width, shoulder width, gutter profile.
• Give the new roadpoint a name which starts off equal to the current roadpoint, and then increments any number found (or adds "001" if none)
• Additionally, the just-added road point should be automatically selected in the scene (so a user can keep pressing "+ Next RoadPoint"), this may require an additional change in the overall addon functionality.
• The newly added RoadPoint should placed directly in front of the current roadpoint by 4x the current lane width in front of the current RoadPoint (via its local Z axis).
  • So if the lane width is 2m, the new roadpoint should be added 8m in front of the current selection)
• As necessary, trigger any updates required to ensure the new generated road segment is immediately visible.
• Possible: if the "next road point" already exists, replace the button with a "Select next" so it's easy to traverse through.
  • In this case, we need two more buttons which are the "Select next" and "Select prior" which are connected to this select function (with an input of the current node & the "direction", either next or prior).
  • If we are to display the select [next/prior] button instead of thead RP, then we just need to hide the add RP button in the ui scene

Out of scope:

• Creating a 3D editor widget, interactive control inside the 3D view (that will be a task after this one)
• Any functionality outside the roadpoint panel

Long term reference mockups

Again, per scope above, we're not making a 3D widget right now, and we're only affecting one roadpoint at a time. However this end still is still helpful as a reference:

Mockup for before/after buttons (part of this PR):

[bdog2112]

• Give the new roadpoint a name which starts off equal to the current roadpoint, and then increments any number found (or adds "001" if none)

RoadPoints should exist in an array where its length, more or less, represents the total number of RoadPoints. Do names matter to the user other than for the purpose of troubleshooting?

What if we simply use the array index number as the name and pad it with zeroes? That would do away with the need to figure out how to extend the number on the current name and it would be really efficient. (e.g. RP00001, RP00002, RP99999)

Using four or five digit padding would give the user between 10K and 100K RoadPoints.

If points are being added/deleted, then a one to one relationship with points and indexes will cease to exist. Still, if we assume that the last RoadPoint in the array is also the last one added, then we can just increment its number to use as the name for the next point without requiring greater complexity.

Is padding even necessary? (e.g. 1, 2, 3... 99999)

[bdog2112]

• The newly added RoadPoint should placed directly in front of the current roadpoint by 4x the current lane width

New segments occasionally display "blank" textures due to their short length resulting from "4 x current lane width". If the segment is, then, stretched slightly longer, the lane texture will show up. This limitation is due to how textures are currently tiled.

A simple tweak that would help to avoid the above problem would be to go with a larger default lane width multiplier such as "5".

There was also some recent discussion about cutting the road texture vertical resolution in half, which might also yield some benefits in texture tiling.

[bdog2112]

There has been some discussion about the node naming algorithm See this post.