autocomplete list behavouir

[Lubomir I. Ivanov]

i've noticed that when doing a fresh start like:
./subsurface ./dives/*

only some of the locations enter the auto-complete list (on my end it
was 9-22 with missing 15). i'm not sure why this is happening, but
there could be some logic of which i'm not aware of as i haven't
checked this much.
also perhaps when the user closes a file we could clear the
auto-complete list i.e. make it local for a file until "close" or
"new" are called.

lubomir
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