Get rid of cryptopp dependency

Plus various code cleanups:
 * More 'auto' usage
 * Use 'nullptr' instead of 0
 * Rename NewApp class to ChronoChatApp
 * Print exception info with boost::diagnostic_information()
 * Disable -Wdeprecated-copy and -Wredundant-tags, they trigger
   too many warnings in Qt headers with gcc 9 and later

Change-Id: I2ea16c19be634f957b59280c704a956f083891f0
diff --git a/test/contact-storage.t.cpp b/test/contact-storage.t.cpp
index a9265e6..c554a58 100644
--- a/test/contact-storage.t.cpp
+++ b/test/contact-storage.t.cpp
@@ -6,7 +6,6 @@
  */
 
 #include "contact-storage.hpp"
-#include "cryptopp.hpp"
 
 #include <boost/test/unit_test.hpp>
 #include <boost/filesystem.hpp>
@@ -14,12 +13,11 @@
 namespace chronochat {
 namespace tests {
 
-using std::string;
 namespace fs = boost::filesystem;
 
 BOOST_AUTO_TEST_SUITE(TestContactStorage)
 
-const string dbName("chronos-20e9530008b27c661ad3429d1956fa1c509b652dce9273bfe81b7c91819c272c.db");
+const std::string dbName("chronos-20e9530008b27c661ad3429d1956fa1c509b652dce9273bfe81b7c91819c272c.db");
 
 BOOST_AUTO_TEST_CASE(InitializeTable)
 {