Add support for merged plots.

[achoum]

Event-set passed in tuples are plotted together.

Example:

tp.plot([
evset_1, # Plot each feature of “evset_1” individually
(evset_1,), # Plot all the features of “evset_1” together
(evset_1[["a", "b"]], evset_2[“c”]), # Plot “a” and “b” from “evset_1”, and “c” from evset_2 together.
])

[DonBraulio]

Cool 🙌
Didn't fully review in-depth but left some comments.

[achoum]

Thanks :)