Small bug when using the -thresh parameter

[Compaile]

Hi,

we found a small bug. When you use the -thresh 0.15 parameter for example during the "detector test" call. The 0.15 gets added into input_fn in run_detector. This is due the Darknet::CfgAndState::process_arguments does not handle params and puts them into additional_arguments. I think the easiest fixt might to skip the next index if the current obj expect a parameter. But since im not quite sure i rather let you decide about the fix

sample command .\darknet.exe detector test .\xy.data .\xy.cfg .\backup\xy_best.weights -thresh 0.1