Trail length viewing options

[keyaloding]

Problem Description

As mentioned in #1769, the GUI currently only allows the user to display trail lengths of up to 250 frames, which can be inadequate for videos longer than 250 frames.

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Feature Proposal

Add 500, 1000, and 2500 as options for the trail length. It will most likely be unnecessary for the max length to be longer than this.

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Implementation Details

Pretty simple change, all it requires is a change in line 51 of sleap/sleap/gui/overlays/tracks.py.

50    def get_length_options(cls):
51        return (0, 10, 50, 100, 250, 500, 1000, 2500) # originally: (0, 10, 50, 100, 250)

[eberrigan]

This was modified 436b177. Should be corrected to check if the length is in the list of options and if not use the value from the preferences. The conditional will most likely be true if trail lengths are used.