Set temprange from 18 to 89 degrees.

There is no need for temperatures under 18 and above 89 degrees. Now it's easier to set the temp.

firmware/weckkubator/weckkubator.ino

@@ -81,5 +81,5 @@ void lcdoutput() {
 // Read Poti
 void settemp() {
   poti = analogRead(A3);
-  tempset = (poti*0.1);
+  tempset = (18+(poti*0.05));
 }