node: Move node code to library.
node: Move UAS to mavros namespace
nodelib: move sources to subdir
node: Catch URL open exception.

Also update connection pointer type.
plugin: sys_status: Move custom mode decoder to UAS.

Issue #136.
node: Implement reverse mode lookup.

Issue #136.
plugin: sys_status: Implement set_mode service.

Previous command shortcut removed.

Issue #136, #134.
scripts: Add mavsys tool.

Implented only `mode` operation.
Issue #134.
scripts: mavsys: Implement set rate command.
return msg generator deps for mavconn
nodelib: add std::array header
Merge branch 'master' into coverity_scan

* master:
  nodelib: add std::array header
  return msg generator deps for mavconn
  scripts: mavsys: Implement set rate command.
  scripts: Add mavsys tool.
  plugin: sys_status: Implement set_mode service.
  node: Implement reverse mode lookup.
  plugin: sys_status: Move custom mode decoder to UAS.
  node: Catch URL open exception.
  nodelib: move sources to subdir
  node: Move UAS to mavros namespace
  node: Move node code to library.