Do not configure the port if talking to PX4 units (since USB does not know anything about baud rate)
Avoid ANY configuration action in serial link if not strictly required by user
Avoid evil port config for CDC devices altogether, non-CDC devices (unknown devices) should be unaffected
Read UART faster to prevent buffer overflows
Merge pull request #471 from thomasgubler/espeak

linux speech synthesis: switch to eSpeak
Merge remote-tracking branch 'upstream/master' into archlinux_dev3
Merge remote-tracking branch 'upstream/no_portconfig' into archlinux_dev3