Merge branch 'master' into 'master'

CI build + tests + fuzzing

See merge request !8

.gitlab-ci.yml

+image: "alpine:latest"
+
+before_script:
+  - apk update && apk add make && apk add g++ && apk add afl && apk add afl-gcc && apk add catch2 && apk add bash
+
+test:
+  stage: test
+  script:
+    - make run_test
+
+fuzz:
+  stage: test
+  script:
+    - make fuzz_calc
+    - ./fuzz_seconds.sh
+  artifacts:
+    paths:
+      - out
+
+build:
+  stage: build
+  script:
+    - make
+  artifacts:
+    paths:
+      - calc
\ No newline at end of file