No general way to determine provider


There is no general way to select a provider. For example, the various tests either do not specify a provider (`rofi_init();`) or assume "verbs" (`rofi_init("verbs",NULL);`). 

This can obviously be fixed for a specific platform if the text string name of the provider is known for that system. Alternatively, should there be a general purpose way for a ROFI application to selecting a provider?