Update lang-nl.js
Update lang-nl.js

Added new strings to Dutch translation (only strings present in lang-de.js; still need to add ~300 strings found in e.g. lang-pt.js).
jmoenig/Snap--Build-Your-Own-Blocks,ericrosenbaum/BeetleBlocks,jmoenig/Snap--Build-Your-Own-Blocks,ericrosenbaum/BeetleBlocks