data: do not encode a Content element if not set
Add Data::hasContent() and Data::unsetContent().
Change the behavior of Interest::setApplicationParameters(Block{}) for
consistency with the corresponding getter and with Data::setContent().
Change-Id: I4cc9058912510db0dfe3da614adee727db149415
diff --git a/docs/doxygen.conf.in b/docs/doxygen.conf.in
index fd5237b..c6aeeb0 100644
--- a/docs/doxygen.conf.in
+++ b/docs/doxygen.conf.in
@@ -836,7 +836,7 @@
# Note that the wildcards are matched against the file with absolute path, so to
# exclude all test directories for example use the pattern */test/*
-EXCLUDE_PATTERNS = */ndn-cxx/impl/* */ndn-cxx/*/impl/*
+EXCLUDE_PATTERNS = */ndn-cxx/impl/* */ndn-cxx/*/impl/* */ndn-cxx/util/nonstd/*
# The EXCLUDE_SYMBOLS tag can be used to specify one or more symbol names
# (namespaces, classes, functions, etc.) that should be excluded from the