ci: Set up SonarCloud

Closes #4.

.travis.yml

@@ -6,8 +6,15 @@ node_js:
   - node
   - lts/*
 
+addons:
+  sonarcloud:
+    organization: diplomatiq
+    token:
+      secure: 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
+
 install: npm ci
 
 script:
   - commitlint-travis
   - npm run build-and-test-everything
+  - sonar-scanner

sonar-project.properties

@@ -0,0 +1,17 @@
+# Standard properties
+sonar.projectKey=Diplomatiq_resily
+sonar.projectName=resily
+sonar.projectVersion=0.0.0
+
+sonar.sources=src
+sonar.tests=test
+sonar.sourceEncoding=UTF-8
+
+# Meta-data for the project
+sonar.links.homepage=https://github.com/Diplomatiq/resily
+sonar.links.ci=https://travis-ci.org/Diplomatiq/resily
+sonar.links.scm=https://github.com/Diplomatiq/resily
+sonar.links.issue=https://github.com/Diplomatiq/resily/issues
+
+# TypeScript-specific properties
+sonar.typescript.lcov.reportPaths=coverage/lcov.info