added github issue form for bug reports

This should hopefully help to get more useful bug reports by making it
more clear what kind of info we need.

Blank issues can still be created but are less p

added github issue form for bug reports

This should hopefully help to get more useful bug reports by making it
more clear what kind of info we need.

Blank issues can still be created but are less prominent. I'm not sure
if we need other types.

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