Add a Travis file

Not really sure how to test this beyond just spamming commits to the
repo until it works, so bear with me

.travis.yml

@@ -0,0 +1,83 @@
+# Optimize git clone
+git:
+    depth: 5
+
+# No need for sudo
+sudo: false
+
+# Bionic is the most recent version of Ubuntu I can get to work properly
+dist: bionic
+
+# Enable C++ language support
+language: cpp
+
+# Cache compiled object files with ccache
+cache: ccache
+
+compiler:
+    - gcc
+#    - clang
+
+os:
+    - linux
+
+addons:
+  apt:
+    sources:
+        - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main'
+          key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+        - sourceline: 'ppa:ubuntu-toolchain-r/test'
+    packages:
+        - make
+        - g++-mingw-w64-x86-64
+
+#env:
+#    - BUILD_TYPE=Debug
+#    - BUILD_TYPE=RelWithDebInfo
+
+before_install:
+    # Set URL for Discord send script
+#    - DISCORD_SEND_SCRIPT_URL=https://raw.githubusercontent.com/DiscordHooks/travis-ci-discord-webhook/master/send.sh
+#    - DISCORD_SEND_SCRIPT_FILENAME=discordSendNotification.sh
+
+    # Display available disk space
+    - df -h
+
+    # Display Travis OS name
+    - echo $TRAVIS_OS_NAME
+
+    # Display build type
+    - echo $BUILD_TYPE
+
+    # Point CC and CXX to MinGW-w64
+    - export CXX="x86_64-w64-mingw32-g++" CC="x86_64-w64-mingw32-gcc" WINDRES="x86_64-w64-mingw32-windres"
+
+    # /usr/bin/gcc points to an older compiler on both Linux and macOS.
+#    - if [ "$CXX" = "g++" ]; then export CXX="g++-9" CC="gcc-9"; fi
+
+    # Display compilers/cmake name/version
+    - echo ${CC}
+    - echo ${CXX}
+    - ${CC} --version
+    - ${CXX} --version
+#    - cmake --version
+
+install:
+    # Get number of cores (or 2 by default if somehow none of these are available somehow)
+    - JOBS=$(nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null || getconf _NPROCESSORS_ONLN 2>/dev/null || echo 2)
+    - echo $JOBS
+
+script:
+    - make -j ${JOBS} FIX_BUGS=1 RELEASE=1 WARNINGS=1 WARNINGS_ALL=1 WINDOWS=1
+
+after_success:
+    # Send success notification to Discord through DISCORD_WEBHOOK_URL
+#    - travis_retry wget ${DISCORD_SEND_SCRIPT_URL} -O ${DISCORD_SEND_SCRIPT_FILENAME}
+#    - chmod +x ${DISCORD_SEND_SCRIPT_FILENAME}
+#    - ./${DISCORD_SEND_SCRIPT_FILENAME} success $DISCORD_WEBHOOK_URL
+
+after_failure:
+    # Send failure notification to Discord through DISCORD_WEBHOOK_URL
+#    - travis_retry wget ${DISCORD_SEND_SCRIPT_URL} -O ${DISCORD_SEND_SCRIPT_FILENAME}
+#    - chmod +x ${DISCORD_SEND_SCRIPT_FILENAME}
+#    - ./${DISCORD_SEND_SCRIPT_FILENAME} failure $DISCORD_WEBHOOK_URL