Add support for texture arrays

[Hopson97]

Suggestion Title Texture Arrays

Describe your suggestion Have texture arrays would allow displaying multiple block types

Implementations ideas [optional] Some kind of interface in src/client/gl/textutes.h like

class TextureArray final {
  public:
    void create();

    // return value being the "layer" added (?)
    int addTexture(const std::string& texture);

    void destroy();
    void bind();

  private:
    unsigned m_textureCount = 0;
    GLuint m_handle = 0;
};