Prepare XMRig-HAC fork for public release

- Add DragonX coin and rx/hush algorithm support
- Update branding to XMRig-HAC / dragonx.is
- Update repository URLs to git.hush.is
- Replace example wallet addresses with placeholders
- Update .gitignore for build directories
- Document fork changes in README and CHANGELOG

src/base/crypto/Coin.h

@@ -42,6 +42,7 @@ public:
         TOWNFORGE,
         YADA,
         HUSH,
+        DRAGONX,
         MAX
     };