Blender Git Loki

Complete fix for [#35769] The �??show texture in texture tab�? button in a modifier does not show up until the user manually shows the texture in the Texture tab (and better fix for [#35741] Material shows WORLD texture_context by default).

Simply recompute texture context on every redraw, like already done for sbuts->texuser (also called texture context :/ ).

Also allows simplification, buttons_check_texture_context can be merged back into set_texture_context...