Add mzscheme to Travis testing

This is an experimental language so needs to go under allow_failures.

.travis.yml

@@ -94,6 +94,11 @@ matrix:
       env: SWIGLANG=lua VER=5.3
       sudo: required
       dist: trusty
+    - compiler: gcc
+      os: linux
+      env: SWIGLANG=mzscheme
+      sudo: required
+      dist: trusty
     - compiler: gcc
       os: linux
       env: SWIGLANG=ocaml
@@ -384,6 +389,12 @@ matrix:
       env: SWIGLANG=octave SWIGJOBS=-j2 VER=4.4 CPP11=1
       sudo: required
       dist: trusty
+    # Experimental languages
+    - compiler: gcc
+      os: linux
+      env: SWIGLANG=mzscheme
+      sudo: required
+      dist: trusty
 
 before_install:
   - date -u

Tools/travis-linux-install.sh

@@ -72,6 +72,9 @@ case "$SWIGLANG" in
 			travis_retry sudo apt-get -qq install lua${VER} liblua${VER}-dev
 		fi
 		;;
+	"mzscheme")
+		travis_retry sudo apt-get -qq install racket
+		;;
 	"ocaml")
 		# configure also looks for ocamldlgen, but this isn't packaged.  But it isn't used by default so this doesn't matter.
 		travis_retry sudo apt-get -qq install ocaml ocaml-findlib