isUnicode renamed to isUTF. Also change UUID regex to lowercase

Hi, As per your suggestions I changed the unicode functions to be named isUTF*. 

Also I changed the UUID regexs to lowercase. According to wikipedia: 

```
In its canonical form, a UUID is represented by 32 lowercase hexadecimal digits, displayed in five groups separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters (32 alphanumeric characters and four hyphens). 
```

So it seems like lowercase is generally correct for UUIDs not uppercase. However I can't really find any other verification for this, and there seems to be both types in use. Either way it should always be all lowercase or all uppercase, never mixed case. So just doing ^[a-zA-Z0-9] would cause problems. Lowercase seems like the best answer.