Sanity checks for input parameters

[skfegan]

Currently the code checks the type for inputs but not whether the values make sense. For example, there is a end parameter for selecting the last frame to analyze but the code does not give a warning if the end value is beyond the number of frames in the trajectory.

Parameters that should be checked

• start : cannot be larger than the number of frames in the trajectory
• end : cannot be larger than the number of frames in the trajectory
• step : negative value would be weird, but I think stepping backwards through the trajectory should be a warning not an error
• bin_width : less than 0 or greater than 360 is wrong; within that range too small or too large would give unreliable results but at this time I am not sure what the limits are.
• temperature : negative is wrong; hotter than the sun is weird
• force_partitioning : ??? What are the physically allowed values? What is the sensible range ... should anyone changing the default get a warning that it should only be changed if you know what you are doing?

[skfegan]

On closer examination, maybe it isn't checking the input types.