[conf] example on how to use SPEECH_NAME
add *.hgt files in srtm folder to gitignore

closes #900
[simulator] NPS: add --time_factor command line option
[nps] always define USE_MISSION_COMMANDS_IN_NPS if mission_rotorcraft module is loaded
Fix bug in datalink
Merge branch 'master' of https://github.com/paparazzi/paparazzi