Add github action configuration for compile test

Add a compilation test configuration file for continuous integration,
similar to Travis-CI (file .travis.yaml in project root directory), but
running as a github action instead. # This is the commit message #2:

.github/workflows/egsnrc.yml

@@ -0,0 +1,49 @@
+name: Compilation test
+
+on:
+
+  push:
+    branches:
+      - master
+      - develop
+
+  pull_request:
+    branches:
+      - master
+      - develop
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+
+      - name: test env variable
+        run: |
+          echo '${{ github.runner.os }}'
+
+      # - name: install dependencies
+      #   run: |
+      #     sudo apt -qq update
+      #     sudo apt install -y gfortran gcc g++
+      #     sudo apt install -y expect
+      #     sudo apt install -y grace
+      #     sudo apt install -y libmotif-dev
+
+      # - name: checkout
+      #   uses: actions/checkout@v3
+
+      # - name: configure
+      #   run: |
+      #     HEN_HOUSE/scripts/configure.expect ${config_name}.conf | tee configure.log
+
+      # - name: report
+      #   run: |
+      #     export EGS_HOME=$HOME/EGSnrc/egs_home
+      #     export EGS_CONFIG=$HOME/EGSnrc/HEN_HOUSE/specs/${config_name}.conf
+      #     source $HOME/EGSnrc/HEN_HOUSE/scripts/egsnrc_bashrc_additions
+      #     for f in HEN_HOUSE/log/*.log configure.log; do echo $f; cat $f; done
+      #     (! grep -i fail configure.log)
+      #     date