please export enc.Base64

[jsparkes]

I am struggling to use Base64 in crypto-ts. I want to return a base64 string of the encryption output. I believe I should use enc.Base64.stringify but I cannot work out how to get it imported using typescript. It looks like it should be added to the following code in src/crypto-ts.ds

    Utf8: typeof Utf8;
    Hex: typeof Hex;
};```

Is it possible to use Base64 in the current version 1.0.2?  Or can we get a new version that makes it available?