Multiple timeouts for shell-integration

[dschep]

Instead of only using the default(per config) backend and one timeout, the shell-integration could support various timeouts with different backends each. For example, local notification if longer than 5 seconds, push notification if longer than a minute.

Config idea:

shell-integration:
  - timeout: 5
    backend: default
  - timeout: 60
    backend: pushover

makes the toplevel shell-integration key special (like backend and backends) Should consider sections? see #124 for more ideas.