Store the HyperlocalSet in a link extension
Mapping for Video.mimes, Companion Banner.mimes
Fix floating-point types to double; mapping from/to micros
DoubleClickCrypto fixes and optimizations

- Encryption and decryption were incorrect for payloads
  of variable size, needing block cypher with >1 block
- Lots of changes for readability, adopting the same
  identifiers used in DoubleClick's crypto specifications
- Some optimizations for buffer usage
Merge pull request #6 from opinali/master

Crypto fixes/opts, float->double fix, mapping mimes and lat/lon