including gl3w before glfw in (especially gl_context)

conanfile.py

include/scigl_render/check_gl_error.hpp

include/scigl_render/gl_context.hpp

include/scigl_render/render/texture_fullscreen_render.hpp

include/scigl_render/scene/cv_camera.hpp

include/scigl_render/shader/shader.hpp

include/scigl_render/shader/single_texture_shader.hpp

package.xml

src/example/scigl_depth_viewer.cpp

src/example/scigl_viewer.cpp

src/gl_context.cpp

src/render/offscreen_render.cpp