[firmware][gui] Extended limits fixes, issue #4447 (#4453)

* [firmware][gui] Adjust custom failsafe (and some channel display) ranges for proper extended limits (fixes #4447).  This also fixes some display issues in *x64 GUIs when adjusting failsafe settings and cleans up code in those functions.

* [firmware][gui] Fix 480x272 channel output progress bars to show full extended limits; Fix alignment issues on all 212x & 480x gui mixes screens with custom channel names; Streamline some channel outputs display code.

* Fix AVR build.

radio/src/gui/128x64/view_channels.cpp

@@ -2,7 +2,7 @@
  * Copyright (C) OpenTX
  *
  * Based on code named
- *   th9x - http://code.google.com/p/th9x 
+ *   th9x - http://code.google.com/p/th9x
  *   er9x - http://code.google.com/p/er9x
  *   gruvin9x - http://code.google.com/p/gruvin9x
  *
@@ -101,11 +101,11 @@ void menuChannelsView(event_t event)
 #endif
 
       // Gauge
-// #ifdef MIXERS_MONITOR
-//       uint16_t lim = mixersView ? 512*2*2 : (g_model.extendedLimits ? 640*2 : 512*2);
-// #else
-//       uint16_t lim = g_model.extendedLimits ? 640*2 : 512*2;
-// #endif
+//      uint16_t lim = (g_model.extendedLimits ? (512 * LIMIT_EXT_PERCENT / 100) : 512) * 2;
+//#ifdef MIXERS_MONITOR
+//      if (mixersView)
+//        lim = 512 * 2 * 2;
+//#endif
       // TODO ? drawGauge(x+LCD_W/2-3-wbar-ofs, y, wbar, 6, val, lim);
 
       ch++;