Add examples for Rng functions.
Clarify comment
Added str::from_slice_with_null() to cast a &[u8] to &str
Added str::subslice_offset()
Renamed slice_bytes_uniqe to slice_bytes_owned
Add example for str::subslice_offset
Fix formatting
auto merge of #5823 : Kimundi/rust/str_from_bytes_slice, r=erickt

Added str::from_bytes_with_null
Added str::subslice_offset
Misc cleanup

Closes #5422
auto merge of #5825 : danluu/rust/rngdoc, r=erickt

This adds an example for most of the methods in Rng.

As a total newcomer to Rust, it took a while to figure out how to do basic things like use library functions, because there aren't many usage examples, and most examples that Google turns up are out of date. Something like this would have saved me a bit of time.

This might be a bit verbose. Some alternative options would be to consolidate all the examples into one section, or to only have code for the specific function call inline.
std: change Encoder variables to be 'e' instead of 's'
core: change result::map{,_err} to consume the result
syntax: Auto derived code should have inherited visibility

This fixes the pretty printer from printing the obsolete syntax
`pub impl...for...`.
Add Dan Luu to the AUTHORS.txt