ENH: move travis support scripts to .travis_scripts

Move the build support scripts for travis to a hidden
subdirectory to keep the top level directory more
clean.

.travis_scripts/travis.install.linux.sh

@@ -0,0 +1,14 @@
+set -vex
+
+wget https://github.com/ninja-build/ninja/releases/download/v1.7.2/ninja-linux.zip
+unzip -q ninja-linux.zip -d build
+
+pip3 install meson
+# /usr/bin/gcc is 4.6 always, but gcc-X.Y is available.
+if [[ $CXX = g++ ]]; then export CXX="g++-4.9" CC="gcc-4.9"; fi
+# /usr/bin/clang has a conflict with gcc, so use clang-X.Y.
+if [[ $CXX = clang++ ]]; then export CXX="clang++-3.5" CC="clang-3.5"; fi
+echo ${PATH}
+ls /usr/local
+ls /usr/local/bin
+export PATH="${PWD}"/build:/usr/local/bin:/usr/bin:${PATH}