Normalize whitespace in source files

Ensure that no source files have trailing whitespace at end of lines and ensure that all files end with a single trailing newline.

This also adds Github Actions to enforce whitespace conventions.

.github/workflow-scripts/check-trailing-newline

@@ -0,0 +1,37 @@
+#!/bin/bash
+
+# Verify that all text files end in a trailing newline.
+
+# Exit on first failing command.
+set -e
+
+# Exit on unset variable.
+set -u
+
+success=0
+
+function is_plaintext_file() {
+  local file="$1"
+  if [[ $file == *.svg ]]; then
+    echo ""
+    return
+  fi
+  file --brief "${file}" | grep text
+}
+
+# Split strings on newlines.
+IFS='
+'
+for file in $(git ls-files)
+do
+  if [[ -z $(is_plaintext_file "${file}") ]]; then
+    continue
+  fi
+
+  if ! [[ -z "$(tail -c 1 "${file}")" ]]; then
+    printf "File must end in a trailing newline: %s\n" "${file}" >&2
+    success=255
+  fi
+done
+
+exit "${success}"

.github/workflow-scripts/check-trailing-whitespace

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+# Check for trailing whitespace at end of lines.
+
+# Exit on first failing command.
+set -e
+# Exit on unset variable.
+set -u
+
+FOUND_TRAILING_WHITESPACE=0
+
+while read -r line; do
+  if grep \
+    "\s$" \
+    --line-number \
+    --with-filename \
+    --binary-files=without-match \
+    --exclude="*.svg" \
+    --exclude="*.eps" \
+    "${line}"; then
+    echo "ERROR: Found trailing whitespace" >&2;
+    FOUND_TRAILING_WHITESPACE=1
+  fi
+done < <(git ls-files)
+
+exit "${FOUND_TRAILING_WHITESPACE}"

.github/workflows/ci.yml

@@ -81,6 +81,17 @@ jobs:
         run: |
           cd src/
           pycodestyle
+  whitespace:
+    runs-on: ubuntu-20.04
+    steps:
+      -
+        name: Ensure there are no trailing spaces
+        run: |
+          .github/workflow-scripts/check-trailing-whitespace
+      -
+        name: Ensure all text files end with a trailing newline
+        run: |
+          .github/workflow-scripts/check-trailing-whitespace
 
   tests:
     runs-on: ubuntu-20.04
@@ -158,7 +169,7 @@ jobs:
         path: src/documents/static/frontend/
 
   build-release:
-    needs: [frontend, documentation, tests, codestyle]
+    needs: [frontend, documentation, tests, whitespace, codestyle]
     runs-on: ubuntu-20.04
     steps:
       -
@@ -268,7 +279,7 @@ jobs:
   build-docker-image:
     if: github.event_name == 'push' && (startsWith(github.ref, 'refs/heads/feature-') || github.ref == 'refs/heads/dev' || startsWith(github.ref, 'refs/tags/ng-'))
     runs-on: ubuntu-latest
-    needs: [frontend, tests, codestyle]
+    needs: [frontend, tests, whitespace, codestyle]
     steps:
       -
         name: Prepare