logger: publish initial logger_status orb message

msg/logger_status.msg

@@ -0,0 +1,20 @@
+uint64 timestamp               # time since system start (microseconds)
+
+uint8 LOGGER_TYPE_FULL    = 0  # Normal, full size log
+uint8 LOGGER_TYPE_MISSION = 1  # reduced mission log (e.g. for geotagging)
+uint8 type
+
+uint8 BACKEND_FILE    = 1
+uint8 BACKEND_MAVLINK = 2
+uint8 BACKEND_ALL     = 3
+uint8 backend
+
+float32 total_written_kb       # total written to log in kiloBytes
+float32 write_rate_kb_s        # write rate in kiloBytes/s
+
+uint32 dropouts                # number of failed buffer writes due to buffer overflow
+
+uint32 buffer_used_bytes       # current buffer fill in Bytes
+uint32 buffer_size_bytes       # total buffer size in Bytes
+
+uint8 num_messages