Maze Teleportation Path

You are given a 2D maze represented as a list of equal-length strings. Each character in the maze can be:

• 'S': the starting position
• 'E': the ending position
• '.': an open space, which you can move into
• '#': a wall, which you cannot move into
• An uppercase letter (e.g., 'A', 'B', 'C', ...): a portal. Each portal letter appears exactly twice in the maze.

When you move into a cell that contains a portal letter, you are immediately teleported to the other cell with the same letter. Note that stepping onto a portal counts as a normal move, and the teleport itself does not require an extra move.

You can move up, down, left, or right from any open cell (or from 'S'). Your goal is to determine the minimum number of steps needed to reach the ending position 'E' from the start 'S'. If 'E' is unreachable, return -1.

Write a function that takes in the maze as a list of strings and returns the minimum number of steps required to travel from 'S' to 'E'.

Example Input:

[
  "S.A",
  "#.#",
  "A.E"
]

In the above example, the optimal path might involve stepping on the portal labeled 'A' to teleport from one location to the other.

Assume the maze dimensions can vary but will always be at least 1x1. Your solution should efficiently determine the shortest path, taking into account both normal moves and teleportation through portals.

Implement your solution in the programming language of your choice.