Doxygen: Do not show private members, referenced by/references relations

This change should help to make the API docs less cluttered.
The above mentioned pieces of information are not very useful for people reading docs - and core developers have their IDEs for checking references.

cmake_templates/Doxyfile.in

@@ -297,7 +297,7 @@ EXTRACT_ALL            = YES
 # If the EXTRACT_PRIVATE tag is set to YES all private members of a class
 # will be included in the documentation.
 
-EXTRACT_PRIVATE        = YES
+EXTRACT_PRIVATE        = NO
 
 # If the EXTRACT_STATIC tag is set to YES all static members of a file
 # will be included in the documentation.
@@ -731,13 +731,13 @@ STRIP_CODE_COMMENTS    = YES
 # then for each documented function all documented
 # functions referencing it will be listed.
 
-REFERENCED_BY_RELATION = YES
+REFERENCED_BY_RELATION = NO
 
 # If the REFERENCES_RELATION tag is set to YES
 # then for each documented function all documented entities
 # called/used by that function will be listed.
 
-REFERENCES_RELATION    = YES
+REFERENCES_RELATION    = NO
 
 # If the REFERENCES_LINK_SOURCE tag is set to YES (the default)
 # and SOURCE_BROWSER tag is set to YES, then the hyperlinks from