New share format. (#13)

* Removing Coverall support until fixed. (See #12)

* Changing Cargo license.

* New wrapping of share data to support signatures.

src/custom_error.rs

@@ -0,0 +1,71 @@
+pub use std::convert;
+pub use std::io::prelude::*;
+
+use std::error;
+use std::fmt;
+use std::io;
+use std::num;
+
+/// Error struct used for generating an `io::Error` from a generic description.
+#[derive(Debug)]
+pub struct Error {
+    descr: &'static str,
+    detail: Option<String>,
+}
+
+impl Error {
+    pub fn new(descr: &'static str, detail: Option<String>) -> Error {
+        Error { descr: descr, detail: detail }
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.detail {
+            None => write!(f, "{}", self.descr),
+            Some(ref detail) => write!(f, "{} ({})", self.descr, detail)
+        }
+    }
+}
+
+impl error::Error for Error {
+    fn description(&self) -> &str { self.descr }
+    fn cause(&self) -> Option<&error::Error> { None }
+}
+
+impl convert::From<Error> for io::Error {
+    fn from(me: Error) -> io::Error {
+        io::Error::new(io::ErrorKind::Other, me)
+    }
+}
+
+/// Returns an `io::Error` from description string and optional detail string.
+/// Particularly useful in `Result` expressions.
+pub fn other_io_err(descr: &'static str, detail: Option<String>) -> io::Error {
+    convert::From::from(
+        Error::new(descr, detail)
+    )
+}
+
+/// maps a `ParseIntError` to an `io::Error`
+pub fn pie2io(p: num::ParseIntError) -> io::Error {
+    convert::From::from(
+        Error::new("Integer parsing error", Some(p.to_string()))
+    )
+}
+
+#[test]
+fn test_custom_error() {
+    let desc = "Boring error description";
+    let detail = "More of it";
+    let ewd = Error::new(desc, Some(detail.to_string()));
+
+    assert_eq!(error::Error::description(&ewd), desc);
+    match error::Error::cause(&ewd) {
+        Some(_)  => assert!(false),
+        None   => assert!(true),
+    }
+    let _formated_err = format!("{}", ewd);
+    let ewod = Error::new(desc, None);
+    let _formated_err = format!("{}", ewod);
+}