[ODE] Info for a new function dJointSetSliderAxisDelta

[Remi Ricard]

Hi Mark
> A few months ago Remi Ricard wrote:
>   
>> Hi,
>>
>> I was looking at the code and Wiki documentation and found this new 
>> function (which is not on the wiki)
>>
>> dJointSetSliderAxisDelta
>>
>> and I wanted to document this new function on the wiki page but there is 
>> a problem I not sure what is the purpose of this function.
>>
>> When there is 2 body to the joint this function does the same thing as 
>> dJointSetSliderAxis  the dx,dy,dz arguments are ignored.
>>
>> N.B. This function was committed on revision 735 and there is no log
>> about this function.
>>
>>   
>>     
>
>
> Remi, did you ever establish the purpose of this function? I'm curious 
> about it, too!
>   
It is looking like you can set the joint such that getPosition will 
return something different than 0.0
after initialization.   But I'm not sure

N.B. I added the + dx, dy, dz when there is 2 body also.

Remi