If you are using SVN (will be in alpha 20), GLSL should now be enabled by default when using a graphic card supporting OpenGL 3+ (cards released in latest 8 years should support it) (r17338). Practically this should, for example, enable windy trees by default (still not advanced graphics effects). This is only effective if you remove any reference to preferglsl in your config files, otherwise the setting in the config files has the precedence. Also if you didn't properly install graphics driver, you'll now get a warning (r17339). And finally settings gentangents=true is no longer needed (you can remove any reference to gentangents in your config files) (r17325). Please test and report any possible problem!