Add highlight to the Travis runs

.travis.yml

@@ -8,5 +8,9 @@ language: go
 go:
   - 1.12.x
 
+before_install:
+  # Needed for test suite to pass
+  - sudo apt-get install -y highlight
+
 script:
   - ./test.sh

README.md

@@ -54,18 +54,27 @@ you can send questions to <johan.walles@gmail.com>.
 Developing
 ----------
 
-Build+ run:
+First, install [Highlight](http://www.andre-simon.de/zip/download.php),
+otherwise the test suite won't pass:
 
-```bash
-./moar.sh
-```
+* On macOS: [`brew install highlight`](https://brew.sh/)
+* On Ubuntu: [`sudo apt-get install highlight`](https://packages.ubuntu.com/search?suite=all&searchon=names&keywords=highlight)
+* Elsewhere, follow [instructions](http://www.andre-simon.de/zip/download.php)
 
-Run integration tests:
+Also, you need the [go tools](https://golang.org/doc/install).
+
+Run tests:
 
 ```bash
 ./test.sh
 ```
 
+Build + run:
+
+```bash
+./moar.sh ...
+```
+
 Making a new Release
 --------------------