changing the loading_ori function for rhori import. By copying the rhori file, locking, etc...

This is working now; we get independent orientation vectors from the .rhori file. To correct this bug, the ori file is locked when read, ensuring that it can only be read by one CPU at a time. Additionally, to avoid repeatedly reading the beginning of the ori file, we copy the ori file and work with the copied file. In this copied file, we erase the lines that have already been processed. It remains to verify that the correct number of lines is erased for each CPU processing. EDIT : It erases the right number of lines.

and to verify robustness (no lagging due to locking files) EDIT it seems now to be robust