Refactor the filtering and paging logic to use several fewer goroutines.
Fixes data race condition with the timing of filter -> pager ->
terminal, can be found when switching message views fast.
Check if filter -> pager process is currently running before calling it
to start again. Fixes data race between fetching message body and
terminal starting. Both can initiate the copying process, and for long
running filters and fast message fetching, it is possible to have
fetched a message but still be running the filter when the terminal
starts.
Move StripAnsi to it's own file in lib/parse, similar to the hyperlinks
parser.
Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Robin Jarry <robin@jarry.cc>
