update gradle project, parallel for-loop based on std::thread on android, fix mipmaps on TextureManager

src/util.h

@@ -75,6 +75,8 @@ inline glm::ivec3 xyz(const glm::ivec4& v) { return glm::ivec3(v.x, v.y, v.z); }
 inline glm::ivec2 zw(const glm::ivec4& v) { return glm::ivec2(v.z, v.w); }
 inline glm::vec2 xy(const glm::vec3& v) { return glm::vec2(v.x, v.y); }
 
+void parallel_for(unsigned nb_elements, std::function<void(int i)> functor, bool use_threads = true);
+
 template<typename T, int N> struct cbuffer
 {
     T m_vec[N];