Add translation for graph header

src/display.cpp

@@ -39,6 +39,7 @@ U8G2_ST7920_128X64_F_HW_SPI display(U8G2_R2, LCD_CS, U8X8_PIN_NONE);
 char* title_pv;
 char* title_battery;
 char* title_grid;
+char* title_graph;
 
 bool pv_charging = false;
 bool show_temp_outside;
@@ -249,7 +250,7 @@ void display_screen_graph(float values[100], char* key, int buffersize)
     logPrintD("Display graph...");
     display.firstPage();
         do {
-            display_header((char*)"Graph");
+            display_header(title_graph);
             display.drawLine(7, 60, 9, 60); //X mark
             display.drawLine(9, 8, 9, 62); //Y boarder
             display.drawStr(1,17, "1");

src/lang.cpp

@@ -32,11 +32,13 @@ void set_display_language(char lang[2])
         title_pv = (char*)"PV Module";
         title_battery = (char*)"Batterie";
         title_grid = (char*)"Netz";
+        title_graph = (char*)"Verlauf";
     }
     else
     {
         title_pv = (char*)"PV modules";
         title_battery = (char*)"Battery";
         title_grid = (char*)"Grid";
+        title_graph = (char*)"Graph";
     }
 }

src/lang.h

@@ -25,5 +25,6 @@
 extern char* title_pv;
 extern char* title_battery;
 extern char* title_grid;
+extern char* title_graph;
 
 void set_display_language(char lang[2]);