Add .travis.yml for continuous integration
Test also with double precision
Merge pull request #178 from scpeters/travis_yml

Add .travis.yml for continuous integration
test commit for travis-ci.org
add option for newer Linux demos to dynamically load X11, glX and OpenGL 1 functions
(and avoid having to link against X, glx and GL)
-DGLEW_INIT_OPENGL11_FUNCTIONS
-DGLEW_DYNAMIC_LOAD_ALL_GLX_FUNCTIONS
-DDYNAMIC_LOAD_X11_FUNCTIONS
and link against libdl (for example usingi -ldl)