Added support for failsafe TAB

Made in cooperation with skaman82.

Summary of modifications:
- Extended data storage to hold data for new/changed MSP messages.
- Added support for added/changed MSP messages.
- Added assigned mode(s) to AUX labels.
- Tooltip changes.
- Included style modifications to configuration tab from Skaman82.
- Moved all texts from failsafe tab .html to `messages.json`.
- Removed failsafe settings from configuration tab (now obsolete).
- Added failsafe-tab variables to Backup & Restore.
- Reorganized stage 2 elements, cleanup and corrections.

js/data_storage.js

@@ -178,3 +178,24 @@ var DATAFLASH = {
     totalSize: 0,
     usedSize: 0
 };
+
+var RX_CONFIG = {
+    serialrx_provider:      0,
+    maxcheck:               0,
+    midrc:                  0,
+    mincheck:               0,
+    spektrum_sat_bind:      0,
+    rx_min_usec:            0,
+    rx_max_usec:            0
+};
+
+var FAILSAFE_CONFIG = {
+    failsafe_delay:                 0,
+    failsafe_off_delay:             0,
+    failsafe_throttle:              0,
+    failsafe_kill_switch:           0,
+    failsafe_throttle_low_delay:    0,
+    failsafe_procedure:             0
+};
+
+var RXFAIL_CONFIG = [];