BRUSSELS, July 20 (Reuters) - Short-video app TikTok on Thursday opened up its research software to researchers in Europe ahead of new EU rules requiring Big Tech to do more to police online content. TikTok, owned by Chinese technology conglomerate ByteDance, is one of 19 online platforms and search engines subject to tougher requirements that will kick in from August under the Digital Services Act (DSA). The company said it was still waiting for the European Commission to set out technical conditions for the application programming interface (API) for accessing its data but decided to go ahead anyway. "TikTok is...