Change references from BTC Core to LTC Core (#373)
Change references from BTC Core to LTC Core (#373)

In this commit, all references to `Bitcoin` or `Bitcoin Core` are replaced with `Litecoin` and `Litecoin Core`, respectively.  

In addition, I added a copyright line for *The Litecoin Core Developers* and provided the rightful attribution to the original `Bitcoin Core` team as per their MIT license.
wangxinxi/litecoin,wangxinxi/litecoin,wangxinxi/litecoin,wangxinxi/litecoin,wangxinxi/litecoin,wangxinxi/litecoin