Close #3732

Most of the "expected" strings in terminal.go test were changed to
"text/template" values. Quotes in those string were parametrized in
the templates. Two functions handling templates were added
for convenience.

Templates has the advantage of:
- parametrize repetitive strings inside "expected" values
  - inner and outer quotes were parametrized in templates
  - long and confusing test values are more readable
- templates can be localized for other operating systems

  # Reload input list with different sources
  seq 10 | fzf --bind 'ctrl-a:reload(seq 100),ctrl-b:reload(seq 1000)'

  # Reload as you type
  seq 10 | fzf --bind 'change:reload:seq {q}' --phony

  # Integration with ripgrep
  RG_PREFIX="rg --column --line-number --no-heading --color=always --smart-case "
  INITIAL_QUERY=""
  FZF_DEFAULT_COMMAND="$RG_PREFIX '$INITIAL_QUERY'" \
    fzf --bind "change:reload:$RG_PREFIX {q} || true" \
        --ansi --phony --query "$INITIAL_QUERY"

Close #751
Close #965
Close #974
Close #1736
Related #1723

- Use bash for `set -o pipefail`
- Fall back to simpler find command when the original command failed

Related: #1061

Instead of notifying the event coordinator (EventBox) whenever a new
line is arrived, start a background goroutine that periodically does the
task. Atomic.StoreInt32 is much cheaper than mutex synchronization
that happens during EventBox update.

    > time cat /tmp/list | fzf-0.10.1-darwin_amd64 --ansi -fqwerty > /dev/null

    real    0m4.364s
    user    0m8.231s
    sys     0m0.820s

    > time cat /tmp/list | fzf --ansi -fqwerty > /dev/null

    real    0m4.624s
    user    0m5.755s
    sys     0m0.732s