name-prefix-list: compare names only in operator==

NamePrefixList type is now a sorted container. The sort() method is
deleted.

The remove() method is renamed to erase(), in accordance with ndn-cxx
code style recommendations.

refs #4094

Change-Id: I2d3f2fa768a8dd9a51108f6f4064243b21fd6df8
diff --git a/tests/test-lsdb.cpp b/tests/test-lsdb.cpp
index f6e078b..526da8a 100644
--- a/tests/test-lsdb.cpp
+++ b/tests/test-lsdb.cpp
@@ -357,7 +357,7 @@
   BOOST_CHECK_EQUAL(nameList, prefixes);
 
   // Remove a prefix: name2
-  prefixes.remove(name2);
+  prefixes.erase(name2);
 
   NameLsa removeLsa(otherRouter, 3, MAX_TIME, prefixes);
   lsdb.installLsa(std::make_shared<NameLsa>(removeLsa));
@@ -367,7 +367,7 @@
 
   // Add and remove a prefix: add name2, remove name3
   prefixes.insert(name2);
-  prefixes.remove(name3);
+  prefixes.erase(name3);
 
   NameLsa addAndRemoveLsa(otherRouter, 4, MAX_TIME, prefixes);
   lsdb.installLsa(std::make_shared<NameLsa>(addAndRemoveLsa));