Update CHANGELOG with the categories for the step 2.3 -> 2.4.

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@10397 2fb0f335-1f38-0410-981e-8018bf24f1b0

CHANGELOG

+Differences Between DuMuX 2.3 and DuMuX 2.4
+===================================================
+
+* IMPROVEMENTS and ENHANCEMENTS:
+
+* IMMEDIATE INTERFACE CHANGES not allowing/requiring a deprecation period:
+
+* Deprecated CLASSES/FILES, to be removed after 2.4:
+
+* Deprecated PROPERTY NAMES, to be removed after 2.4: BEWARE: The compiler will
+  not print any warning if a deprecated property name is used.
+
+* Deprecated CONSTANTS/ENUMS, to be removed after 2.4: BEWARE: The compiler will
+  not print any warning if a deprecated constant/enum is used.
+
+* Deprecated public MEMBER VARIABLES, to be removed after 2.4: BEWARE: The
+  compiler will not print any warning if a deprecated public member variable 
+  is used.
+
+* Deprecated MEMBER FUNCTIONS, to be removed after 2.4:
+
+* DELETED classes/files, property names, constants/enums, 
+  member functions/variables, which have been deprecated in DuMuX 2.3:
+  Everything listed as deprecated below has been removed.
+
+
 Differences Between DuMuX 2.2 and DuMuX 2.3
 ===================================================