Changes are not counted perfectly

[d-Rickyy-b]

The calculation of changes is still buggy. Imagine 2 days being compared. In the newer one, there are 3 new elements and one element missing.

L1	L2
1	1 -> x
2	3 -> u
5	5 -> x
7	  -> u
9	  -> u

x = not unique
u = unique

MGGVertretungsplan/app/src/main/java/de/aurora/mggvertretungsplan/datamodel/TimeTableDay.java

Lines 118 to 121 in 01c6f43

	if (getCancellations() >= ttd.getCancellations())
	diffs += getUniques(timeTableElements, ttd.getElements());
	else
	diffs += getUniques(ttd.getElements(), timeTableElements);

Use symmetric differences (set theory) to calculate the real differences, as shown here!

Maybe even create seperate lists for each day, so that the notification(s) contain the day of the changes.