pressure trend: arrows

src/main.cpp

@@ -279,15 +279,15 @@ void displayValues() {
     display.setCursor(135,y_offset+45);
     if (isnan(pressure_diff) || history_pressure.getCount() < history_pressure.getSize()) {
     } else if (pressure_diff > -20 && pressure_diff < -1.1) {
-      display.print("Trend: --");
+      display.print("Trend: \x19\x19");
     } else if (pressure_diff < -0.2) {
-      display.print("Trend: -");
+      display.print("Trend: \x19");
     } else if (pressure_diff < 0.2) {
-      display.print("Trend: =");
+      display.print("Trend: \x1a");
     } else if (pressure_diff < 1.1) {
-      display.print("Trend: +");
+      display.print("Trend: \x18");
     } else if (pressure_diff < 20) {
-      display.print("Trend: ++");
+      display.print("Trend: \x18\x18");
     } else {
       display.print("?");
     }