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/.jenkins.d/00-deps.sh b/.jenkins.d/00-deps.sh
index 34d006e..32278a1 100755
--- a/.jenkins.d/00-deps.sh
+++ b/.jenkins.d/00-deps.sh
@@ -8,20 +8,16 @@
     fi
 
     if [[ -n $GITHUB_ACTIONS ]]; then
-        # Homebrew doesn't have cryptopp packages, so build from source
-        git clone https://github.com/weidai11/cryptopp/
-        cd cryptopp
-        make -j4
-        make install
-        cd ..
-
-        # Travis images come with a large number of pre-installed
-        # brew packages, don't waste time upgrading all of them
+        # Don't waste time upgrading all pre-installed packages
         for FORMULA in "${FORMULAE[@]}"; do
             brew list --versions "$FORMULA" || brew install "$FORMULA"
         done
 
-        brew link qt --force
+        # Ensure /usr/local/opt/openssl exists
+        brew reinstall openssl
+
+        # Homebrew qt is keg-only, force symlinking it into /usr/local
+        brew link --force qt
     else
         brew update
         brew upgrade
@@ -31,7 +27,7 @@
 
 elif has Ubuntu $NODE_LABELS; then
     sudo apt-get -qq update
-    sudo apt-get -qy install g++ pkg-config python3-minimal \
+    sudo apt-get -qy install build-essential pkg-config python3-minimal \
                              libboost-all-dev libssl-dev libsqlite3-dev \
-                             libcrypto++-dev qt5-default
-fi
\ No newline at end of file
+                             qt5-default
+fi