Remove travis build

.travis.yml

@@ -1,22 +0,0 @@
-language: c
-sudo: false
-after_success: bash <(curl -s https://codecov.io/bash)
-branches:
-  only:
-    - 7.0
-os:
-  - linux
-  - osx
-#  - windows
-compiler:
-  - clang
-  - gcc
-script: make mg_prefix cpp test ex
-matrix:
-  include:
-    - os: linux
-      compiler: msvc98
-      script: make vc98 vc2017
-      sudo: required
-      services:
-        - docker