Transfer route using RTE and WPL sentences

[msallin]

As the intent of NMEA 0183 RTE & WPL Sentences is to transfer routes and waypoints between devices, often initiated manually, it seems more appropriate for SignalK to maintain a database of routes & waypoints populated either by importing GPX files, receiving NMEA 0183 RTE & WPL Sentences or receiving NMEA PGN's 130065, 130067,130074 etc. and with the generation and transmission initiated by user action. (origin: #153 (comment))

---

There is currently no RTE (Route) sentence generator.

$--RTE transmits route information (ordered list of waypoint IDs) to downstream devices, enabling full route transfer from Signal K to plotters and autopilots.

Format:

$--RTE,x,x,a,c--c,c--c,...,c--c*hh
total msg# type routeName wp1 wp2 ... wpN

Long routes need to be split across multiple sentences. The route data should come from the Signal K course/route information.

---

There is currently no WPL (Waypoint Location) sentence generator.

$--WPL transmits waypoint coordinates and identifier to downstream devices (plotters, autopilots), allowing them to store waypoints defined in Signal K.

Format:

$--WPL,llll.ll,a,yyyyy.yy,a,c--c*hh
lat N/S lon E/W name

---

This feature needs design (e.g. how to kick-off a transfer etc)