similarity detection: filter unimportant words out

[tstromberg]

We can get a higher hit-rate for similarity if we filter out a basic list of words which don't impact the nature of an issue or PR:

There are certain adjectives and prepositions that come to mind:

a
about
an
and
are
be
by
can
completely
does
extremely
for
has
have
how
in
is
maybe
of
on
or
should
some
something
still
than
the
then
to
use
very
via
when
why
with

However: we need to be careful not to skew things so badly that the min-similarity index is no longer helpful.

[tstromberg]

If someone wants to take it this on, I recommend adding the code within compressTitle:

triage-party/pkg/hubbub/similar.go

Line 27 in 8ee4505

func compressTitle(t string) string {