[request] Check many trees at once to color a progression path

Check for duplicates

• I've checked for duplicate open and closed issues by using the search function of the issue tracker

What platform are you running Path of Building on?

Windows

Is your feature request related to a problem?

Currently, we can pick at most two different trees and compare them. When using league starter guides, people usually create multiple "checkpoints", so I'd like to be able to quickly see where I'm at and what are the immediate next recommended nodes to pick on the tree.

Describe the solution you'd like

For example, this photo is lvl 32 to lvl 40.

With this open, I can understand what path I should take from 32 to 40, whereas if I only keep my lvl 40 tree open, I may pick some suboptimal nodes before. The solution is to allow multiple trees to be picked, specially following a certain order, and color nodes to make it easy to understand the proposed path between them.

An extension of this idea is to set Path of Building to track a certain character (level or full tree) from an account and just do the delta between the currently selected tree and the fetched tree.

Describe alternatives you've considered

I can achieve this by manually changing trees to compare after each checkpoint.

Additional context

This looks like the idea proposed in #2141, currently implemented, but for multiple trees, and focusing on a clear progression of trees T1 -> T2 -> T3, instead of just comparing different nodes. Just being able to compare more than two trees at once would be wonderful.

Start by reviewing the existing two-tree comparison described as issue #2141 and how tree checkpoints are represented in Path of Building. Define how an ordered set of trees should display each progression path, including the optional account-tracking extension; done means multiple checkpoints can be selected and their node deltas are clearly colored.