Revert "remove Travis: GitHub CI is a lot faster and more reliable"

This reverts commit 9d1814ab81.

.travis.yml

@@ -0,0 +1,89 @@
+language: c
+matrix:
+  include:
+    - os: linux
+      name: "linux"
+      dist: xenial
+      sudo: required
+      addons:
+        apt:
+          packages:
+            - build-essential
+            - libglfw3
+            - libglfw3-dev
+            - libfreetype6-dev
+            - libssl-dev
+    - os: windows
+      name: "windows_gcc"
+      language: bash
+      filter_secrets: false
+    - os: windows
+      name: "windows_msvc"
+      language: bash
+      filter_secrets: false
+    - os: osx
+      name: "osx"
+      osx_image: xcode10.3
+      addons:
+        homebrew:
+          packages:
+            - freetype
+            - glfw
+            - openssl
+script:
+  - |
+    if [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
+      export LIBRARY_PATH=$LIBRARY_PATH:/usr/local/opt/openssl/lib/
+    fi
+  - |
+    if [[ "${TRAVIS_OS_NAME}" == "windows" ]]; then
+      ### troubleshooting and diagnostics: show ALL environment variables in the instance
+      #set
+      set -e
+      git clone --depth=1 https://github.com/ubawurinna/freetype-windows-binaries  thirdparty/freetype/
+
+      if [[ "${TRAVIS_JOB_NAME}" == "windows_gcc" ]]; then
+        echo "Building V with GCC"
+        export VFLAGS="-os windows"
+        ./make.bat -gcc
+      fi
+      if [[ "${TRAVIS_JOB_NAME}" == "windows_msvc" ]]; then
+        echo "Building V with MSVC"
+        export VFLAGS="-os msvc"
+        ./make.bat -msvc
+      fi
+
+      ./v.exe test v
+      set +e
+    fi
+  - |
+    if [[ "${TRAVIS_OS_NAME}" != "windows" ]]; then
+      make
+      ./v -o v compiler
+      ./v test v
+    fi
+  - |
+    if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
+      ## aliases do not work for some reason in travis, just use full commands :-|
+      echo "Nodejs version:"
+      node --version      
+      # Build hi.js
+      echo "fn main(){ println('Hello from V.js') }" > hi.v
+      ./v -o hi.js hi.v
+      node hi.js
+    fi
+  - |
+    if [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
+      echo "Nodejs version:"
+      node --version      
+      # Build hi.js
+      echo "fn main(){ println('Hello from V.js') }" > hi.v
+      ./v -o hi.js hi.v
+      node hi.js
+    fi
+  - |
+    if [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
+      # Build Vid
+      git clone https://github.com/vlang/vid
+      cd vid && ../v -debug -o vid .
+    fi