Add short and long utterances on token count plot

[gabegma]

Resolve #94

Description:

Self-explanatory :)

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[gabegma]

Only this code is new, the one above was just moved in an else so it is only computed when data is available.

[JosephMarinier]

Beautiful! 👌 And useful, I think. 👍

[JosephMarinier]

By the way, that's a detail, but you could avoid the zip() by defining the lists/tuples in the other "direction", like

Suggested change

	for threshold, edge, pretty_name, xanchor in zip(
	[
	syntax_options.short_utterance_max_word + 0.5,
	syntax_options.long_utterance_min_word - 0.5,
	],
	[0, max_x + 1],
	["Short utterances", "Long utterances"],
	["right", "left"],
	):
	for threshold, edge, pretty_name, xanchor in (
	(syntax_options.short_utterance_max_word + 0.5, 0, "Short utterances", "right"),
	(syntax_options.long_utterance_min_word - 0.5, max_x + 1, "Long utterances", "left"),
	):