Merge pull request #905 from lemire/master

adding the roaring library (compressed bitset format)

README.md

@@ -210,6 +210,7 @@ Please take a quick gander at the [contribution guidelines](https://github.com/a
 * [golang-set](https://github.com/deckarep/golang-set) - Thread-Safe and Non-Thread-Safe high-performance sets for Go.
 * [goskiplist](https://github.com/ryszard/goskiplist) - A skip list implementation in Go.
 * [mafsa](https://github.com/smartystreets/mafsa) - MA-FSA implementation with Minimal Perfect Hashing
+* [roaring](https://github.com/RoaringBitmap/roaring) - Go package implementing compressed bitsets.
 * [skiplist](https://github.com/gansidui/skiplist) - Skiplist implementation in Go
 * [trie](https://github.com/derekparker/trie) - Trie implementation in Go
 * [ttlcache](https://github.com/diegobernardes/ttlcache) - An in-memory LRU string-interface{} map with expiration for golang