Faster hashing

1000000 Hashes
```
SM Timing
-----------
SizeT hash 	      1	00.061367	(00.061367 +- 00.000000)	[00.061367,00.061367]
String hash	      1	01.651815	(01.651815 +- 00.000000)	[01.651815,01.651815]
```
Couldn't we also provide a flavor without the magic number multiplication for applications that are confident that the hashid they use comes from a uniform enough distribution?