fixed slicing for images with the condition totalPixels/threadCount != Integer

Co-authored-by: darkress <30271678+DarkressX@users.noreply.github.com>
Reviewed-on: darkress/PixelFloodClient#2

de/darkress/pixelfood/Main.java

@@ -91,9 +91,11 @@ class Main
 
     public static String[] prepareThreadArray(ArrayList<String> fullArray, int threadNumber, int threadCount)
     {
-        String[] threadArray = new String[fullArray.size()/threadCount];
         int count = 0;
-        for(int i = (threadNumber*fullArray.size())/threadCount; i < ((threadNumber+1)*fullArray.size())/threadCount; i++)
+        int arrayStart = (threadNumber*fullArray.size())/threadCount;
+        int arrayEnd = ((threadNumber+1)*fullArray.size())/threadCount;
+        String[] threadArray = new String[arrayEnd-arrayStart];
+        for(int i = arrayStart; i < arrayEnd; i++)
         {
             threadArray[count] = fullArray.get(i);
             count++;