SPRINGFIELD — First, there was the web. Then, social media.Now, the cutting-edge technology that powers cryptocurrencies like Bitcoin could be at the heart of a third wave of digital innovation.That’s what some Illinois lawmakers and government officials think, at least. And it’s why they held a joint committee hearing this week to explore blockchain, an unchangeable, sequential ledger of transactions that could beef up virtual security.If the internet started as a way to connect users in chat rooms and …