Refactor and modernize namespace declarations

 * Completely remove inline namespace v2
 * Flatten some unnecessarily deep namespace nesting
 * Move DummyClientFace, Segmenter, SegmentFetcher to namespace ndn
 * Move all unit tests to namespace ndn::tests

Change-Id: I8bcfcf9fd669936a3277d2d5d505f765b4b05742
diff --git a/tests/unit/name-component.t.cpp b/tests/unit/name-component.t.cpp
index a35f980..d72de0f 100644
--- a/tests/unit/name-component.t.cpp
+++ b/tests/unit/name-component.t.cpp
@@ -30,9 +30,10 @@
 #include <boost/lexical_cast.hpp>
 #include <boost/mpl/vector.hpp>
 
-namespace ndn {
-namespace name {
-namespace tests {
+namespace ndn::tests {
+
+using ndn::name::Component;
+using ndn::name::UriFormat;
 
 BOOST_CONCEPT_ASSERT((boost::EqualityComparable<Component>));
 BOOST_CONCEPT_ASSERT((WireEncodable<Component>));
@@ -616,6 +617,4 @@
 
 BOOST_AUTO_TEST_SUITE_END() // TestNameComponent
 
-} // namespace tests
-} // namespace name
-} // namespace ndn
+} // namespace ndn::tests