[phobos] std.base64 replacement

[Masahiro Nakagawa]

Current std.base64 is not Boost License.

So, I wrote base64 module.

http://bitbucket.org/repeatedly/scrap/src/tip/base64.d

This module is based on RFC4648 and faster than std.base64.
In addition, User can encode / decode modified Base64 format using  
Base64Impl.

What do you think?


Masahiro