allow writing zeroes as decimal values

app/src/main/java/calculator/simplemobiletools/com/CalculatorImpl.java

@@ -76,6 +76,11 @@ public class CalculatorImpl {
     }
 
     private String formatString(String str) {
+        // if the number contains a decimal, do not try removing the leading zero anymore, nor add group separator
+        // it would prevent writing values like 1.02
+        if (str.contains("."))
+            return str;
+
         final double doubleValue = Formatter.stringToDouble(str);
         return Formatter.doubleToString(doubleValue);
     }