Study: Add the possibility to handle Transpositions

[poettler-ric]

I am using a Study to build my repertoire. Often there are transpositions from one position/opening/variation to another one. It would be nice if there was some kind of automatism to detect and handle those instead of manually keeping track of them and noting them in handwritten comments.
Some thoughts:

• It would be nice if it were possible to click on the transposition and it takes me to the tree it links to
• Also nice would be the possibility to right-click on such an transposition link and pull the tree it links to here and change the old links to the new location of the continuation (like making it the new mainline).
• Repetitions might cause problems to an automatism

[Siderite]

The LiChess Tools browser extension highlights transpositions to the current move. You can even show all transposing moves in an entire PGN and see next moves from transpositions as well.