minor changes to the .txt files

expressions.txt

@@ -3,4 +3,8 @@ x
 4+2
 3+(2^3)
 2*2*2+3
-(23+2*(2*3))-5
+(23+2*(2*3))-5
\ No newline at end of file
+1 + x*y^2 - (31 * x)-y
+1 + x^2 - (3 * x)
+2-x + 0.5*x^2 - 1
+(5*2-(5^2)+3*(201.01-15))
\ No newline at end of file

to-do.txt

-2. Testklassen
-
-3. Visitor pattern
-4. plot function
-5. Überarbeiten
--> Dokumentation
--> Exceptions
--> Kommentare
--> Code strukturieren
\ No newline at end of file