Save alias (#1852)

* figuring out error with lines

* make progress in printing of block

* support for external commands; fix some tiny bugs in formatting

* basic printing of block; going to experiment with bubbling raw input to the command itself to avoid potential edge cases

* remove fmt::Display impls for hir structs; bubbled raw_input to command args

* compiling checkpoint :)

* process raw input alias to remove save flag; do duplicates stored

* fix warnings; run clippy

* removed tmux log file

* fix bug in looking for same alias; changed unwraps to safe unwraps

crates/nu-protocol/src/hir.rs

@@ -1,6 +1,6 @@
 use std::cmp::{Ord, Ordering, PartialOrd};
+use std::convert::From;
 use std::hash::{Hash, Hasher};
-
 use std::path::PathBuf;
 
 use serde::{Deserialize, Serialize};