reinstantiated better helppatch for SolvePnP

i made this into an extra PR so you can choose. 
some time ago i commited this SolvePnP helppatch to the pack and you accepted it. i now noticed that it was replaced with another patch which i'd argue is not a very good helppatch for SolvePnP. even mine is not perfect, but  a much better start as it goes well together with the helppatch of CalibrateCamera. 

so in case this overwriting was not on purpose i'd be happy to see this one back in the pack.