Merge pull request #844 from iNavFlight/agh_osd_rpm

[OSD] Add support for configuring OSD_ESC_RPM element

Author: DzikuVx

_locales/en/messages.json

@@ -2721,6 +2721,9 @@
     "osdElement_VTX_POWER_HELP": {
         "message": "Shows the current VTX power level. Blinks when the corresponding RC adjustment is selected"
     },
+    "osdElement_ESC_RPM": {
+        "message": "Motor RPM from ESC telemetry"
+    },
     "osdElement_VTX_CHANNEL": {
         "message": "Video TX Band and Channel"
     },

tabs/osd.js

@@ -764,6 +764,12 @@ OSD.constants = {
                     id: 104,
                     preview: 'MSP'
                 },
+                {
+                    name: 'ESC_RPM',
+                    id: 106,
+                    min_version: '2.3.0',
+                    preview: FONT.symbol(SYM.THR) + '983',
+                }
             ]
         },
         {