scripts: Initial import mavteleop

Now it's just proof of concept.
Implemented only RC override of RPYT channels.

Issue #133.
scripts: mavsetp: changed the way offboard mode is switched
travis: use actual branch that we test, not master
Merge pull request #140 from TSC21/mavsetp

scripts: mavsetp: changed the way offboard mode is switched
scripts: mavsetp: added local accel; corrected how the OFFBOARD mode is swtch.
scripts: mavsetp: corrected msg API; mavteleop: added prefix to rc override
scripts: mavsetp: corrected API; added possibility of parse angles in dg or rad
Merge pull request #141 from TSC21/mavsetp

scripts: mavsetp: added local accel; corrected how the OFFBOARD mode is switched
Update doxygen documentation.

Add split lines in UAS, and make UAS.connection atomic.
Add rosdoc configuration for mavros_extras.
scripts: mavsetp: Fix twist.angular vector construction.

Small style fix.
launch files: added px4 launch files for connection with radio and gcs
scripts: mavsetp: Fix misprint.
launch: corrected launch for gcs bridge
Merge pull request #142 from TSC21/launch_improve

Launch files update
Move common cmake rules to modules.

Same mech as in `cmake_modules` package.
Issue #139.
extras: Use cmake modules.

Issue #139.
cmake: Add check MAVLINK_DIALECT value

Fix #139.
Merge branch 'master' into coverity_scan

* master:
  cmake: Add check MAVLINK_DIALECT value
  extras: Use cmake modules.
  Move common cmake rules to modules.
  launch: corrected launch for gcs bridge
  scripts: mavsetp: Fix misprint.
  launch files: added px4 launch files for connection with radio and gcs
  scripts: mavsetp: Fix twist.angular vector construction.
  Update doxygen documentation.
  scripts: mavsetp: corrected API; added possibility of parse angles in dg or rad
  scripts: mavsetp: corrected msg API; mavteleop: added prefix to rc override
  scripts: mavsetp: added local accel; corrected how the OFFBOARD mode is swtch.
  travis: use actual branch that we test, not master
  scripts: mavsetp: changed the way offboard mode is switched
  scripts: Initial import mavteleop