First installment of tech ENABLE_SHADERS_MANAGER, using class GLShadersManager as a central point to manage OpenGL shaders

src/slic3r/GUI/GLShadersManager.hpp

@@ -0,0 +1,31 @@
+#ifndef slic3r_GLShadersManager_hpp_
+#define slic3r_GLShadersManager_hpp_
+
+#if ENABLE_SHADERS_MANAGER
+
+#include "GLShader.hpp"
+
+#include <vector>
+#include <string>
+#include <memory>
+
+namespace Slic3r {
+
+class GLShadersManager
+{
+    std::vector<std::unique_ptr<GLShaderProgram>> m_shaders;
+
+public:
+    std::pair<bool, std::string> init();
+    // call this method before to release the OpenGL context
+    void shutdown();
+
+    // returns nullptr if not found
+    GLShaderProgram* get_shader(const std::string& shader_name);
+};
+
+} // namespace Slic3r
+
+#endif // ENABLE_SHADERS_MANAGER
+
+#endif //  slic3r_GLShadersManager_hpp_