Fluid usage recommendations

`FluidParser` and `TemplateOptions` should be singletong instances. Make sure a single instance of these are created and reused. `TemplateContext` is the only thing that should be created per rendering. If you are using DI just make these singletons. Otherwise ensure they are static, or fields of a class that is instanciated only once. Then enjoy the perf gains ;) (probably * 50 for rendering)