Implement ByteVectorValue

This appears to implement all the functionality required by R7RS.
Additionally, this implements StringValue::toUtf8ByteVector() to support
(string->utf8)
Include <string.h> for memcmp

This is required to compile on Ubuntu 13.10
Implement VectorValue

This implements everything in R7RS except for string and list
conversions. This will require better Character and list support,
respectively.
Add writers for Vector, ByteVector, Procedure

Procedures just display "#!procedure" as its not possible to recover
their source. Vectors and bytevectors use their R7RS external form
Quote symbols with non-ASCII characters

From R7RS: "Symbols that contain non-ASCII characters are escaped with
vertical lines"