Add /loadalign, /loadaligntest, /correctorigin, and helpers

/correctorigin = move pos1 and pos2 to correct origin (ie pos1 located with minimum x,y,z, pos2 with maximum x,y,z)
/loadalignoffset = sets or clears an offset to the player (or pos1) location for /loadalign
/loadalign = load schem file at player location, aligned to forward direction
/loadaligntest = test run of /loadalign (ie mark location, but don't place any nodes)
/loadalignpos = load schem file at pos1 location, aligned to forward direction
/loadalignpostest =  = test run of /loadalignpos (ie mark location, but don't place any nodes)