Handle focus reporting race

[tfpf]

• Disable focus reporting after reading standard input
  • Some slow terminals may batch process the enable and disable requests if they are sent in succession.
  • The terminal may then not send focus escape sequences at all.
• Make the standard input read time out from the start of the read instead of after a byte is available
  • The aforementioned slow terminals may not send escape sequences, so the read will then block forever.
• Check for errors getting or setting terminal attributes before enabling focus reporting
• Clear standard input before enabling focus reporting