Texture creation refactoring + texture filtering options

[tomangelo]

I write this post because I want to encourage more involvement in the project of various people, not just few programmers. Someone could help decide where and how to put things in graphics option menu.

Graphics option menu is best choise, but it will be a little overloaded. We should pack some current options from this menu to another, so we could add these new options instead. I mean these checkboxes from the left side would go to submenu "Details", if it's possible with current code.
When we'll have some free space, we could add list with possible options for Texture filtering option (Nearest/Bilinear/Trilinear), below Mipmap level with settings 4,8,16, silimar like current "Number of Particles" options from the right side. It it will be impossible to implement, then maybe some "hack", like "if it's 1, then display 4, when 2, then it's 8, etc...", I don't know what's possible with our current UI, and refactoring UI is planned on 0.3.0. Finally, Anisotropy level with similar 'display system' like Mipmap level option.