Update for latest rust language changes.
Merge branch 'rust-master' of https://github.com/am0d/rust-pcre into master

Conflicts:
	src/pcre/pkg.rs
Clean up println!()s

When the string is a valid format string, there is no need for a "{}" format
string.
Write error messages to stderr
Use BufferedReader from std::io

Update for mozilla/rust@295b46f - Tweak the interface of std::io
Update the README