define new B2.Divide and B2.Subtract class

- defined Config#USER_STEPS_PARSER flag to enable the parsing

See this link for motivation
- https://blog.socratic.org/stepping-into-math-open-sourcing-our-step-by-step-solver-9b5da066ae36

symja_android_library/matheclipse-core/src/main/java/org/matheclipse/core/basic/Config.java

@@ -204,9 +204,12 @@ public static Cache<IExpr, Object> getExprCache() {
   /** Set to true if in fuzz testing mode */
   public static boolean FUZZ_TESTING = false;
 
-  /** Set to true if the fuzzy parser should be used in the free form Symja API */
+  /** Set to <code>true</code> if the fuzzy parser should be used in the free form Symja API */
   public static boolean FUZZY_PARSER = false;
 
+  /** Set to <code>true</code> if the parser should be used to map the user input exactly */
+  public static boolean USER_STEPS_PARSER = false;
+
   /**
    * Show the console output, if an expression has a head symbol with attribute <code>
    * ISymbol.CONSOLE_OUTPUT</code>.