Add command to replace block types {x1,x2,...,xn} -> {y1,y2,...,yn} with a 1:1 mapping

WORLDEDIT-2874 - Reported by Eaglebird

I realized a few moments ago that //replace, or worldedit itself, does not support multiple block specifications for the "" of the replacement. I discovered this when my pile of diamond blocks and pile of emerald blocks became intermingled when I selected them and tried to switch them using //replace diamond_block,emerald_block emerald_block,diamond_block.

Logically, replace the first block of the target with the first block of the payload, second block with second block, third with third, etc. so that multiple replacements can be done in a selection at once. This might allow users to build their homes out of any material and change the theme or look with a simple selection and replacement.

Syntax could be similar to the current syntax, "//replace ", "//replace iron_block,diamond_block,50 gold_block,iron_block,glowstone", and if they don't match up as singles or a list, show the player an error.