Use new Doxygen script in Travis CI

Remove the old `travis_doxygen.sh` script and associated part of
`run_diff.sh`, and change `.travis.yml` to use the new `run_doxygen.sh`
instead.  The new script should report new problems (and not report
already existing problems) more reliably than the old script which
relied on the line numbers reported by Doxygen.

Author: John Nonweiler

.travis.yml

@@ -72,7 +72,7 @@ jobs:
       script:
         - echo $PATH
         - doxygen --version
-        - scripts/travis_doxygen.sh
+        - scripts/run_doxygen.sh
       before_cache:
       after_success:
         # Google Cloud Integration

scripts/run_diff.sh

@@ -5,7 +5,7 @@ set -e
 script_folder=$(dirname "$0")
 absolute_repository_root=$(git rev-parse --show-toplevel)
 mode=$1
-modes="CPPLINT | DOXYGEN"
+modes="CPPLINT"
 
 if [[ "$#" -gt 3 ]]
 then
@@ -39,23 +39,6 @@ then
   else
     cmd='${script_folder}/cpplint.py --filter=-whitespace/operators,-readability/identifier_spacing $file 2>&1 >/dev/null'
   fi
-elif [[ "$mode" == "DOXYGEN" ]]
-then
-  doxygen=doxygen
-  doxygenlogdir="doc/html"
-  doxygenlog="$doxygenlogdir/doxygen.log"
-  suppress_warnings=(
-    "warning: Included by graph for .* not generated, too many nodes. Consider increasing DOT_GRAPH_MAX_NODES.")
-  if ! $doxygen --version &>/dev/null
-  then
-    echo "Doxygen is not installed on this PC"
-    echo "Please install before running this script"
-    exit 1
-  else
-    mkdir -p $doxygenlogdir && cd src && $doxygen &> ../$doxygenlog && cd ..
-    suppress_warnings_regex=$(IFS="|" ; echo "${suppress_warnings[*]}")
-    cmd='grep -Ev "$suppress_warnings_regex" $doxygenlog'
-  fi
 else
   echo "Mode $mode not recognized"
   echo "Possible values: $modes"