Modify how tests are run to improve overall speed.

A Vader issue causes problems with the test results when using the
location list. Because of this the tests were modified to run 1 test
file per vim instance instead of running all tests in a single vim
instance. This resulted in signficant slow down in test execution time.
To speed up execution time only specific tests are run individually now.

test/run_tests.sh

@@ -36,11 +36,20 @@ runVader() {
         echo ""
         echo "Running version: $v"
         vim="/vim-build/bin/$v -u test/vimrc -i NONE"
-        test_cmd="for VF in test/*.vader; do $vim \"+Vader! \$VF\"; done"
+        test_cmd="for VF in test/independent_runs/*.vader; do $vim \"+Vader! \$VF\"; done"
+
         set -o pipefail
+
+        # tests that must be run in individual vim instances
+        # see README.md for more information
         docker run -a stderr -e VADER_OUTPUT_FILE=/dev/stderr "${flags[@]}" \
           /bin/bash -c "$test_cmd" 2>&1 | vader_filter | vader_color
+
+        # remaining tests
+        docker run -a stderr -e VADER_OUTPUT_FILE=/dev/stderr "${flags[@]}" \
+          "$v" -u test/vimrc -i NONE "+Vader! test/*" 2>&1 | vader_filter | vader_color
         set +o pipefail
+
     done
 }