[Therion] changed definition of drawing of centreline

Hi Interested in the change <https://therion.speleo.sk/wiki/examples?do=diff&rev2%5B0%5D=1546628211&rev2 %5B1%5D=1546628298&difftype=sidebyside> to the line survey (centreline) examples in the wiki that Martin just made (I'm up for a modest amount of metapost learning). I can follow what the new more complicated metapost is doing, and can understand that it might be better practice to do it that way. But is there no place for the more direct and simpler 'draw p' approach? Or did it not work? (I have not tested them). Perhaps both versions could be listed on the wiki, with some comment about pros and cons or why one approach is better than the other? Bruce