Revert to term_size

Git invokes difftastic and then pipes stdout to less, but stderr still
goes to the terminal. term_size queries both stdout and stderr, so it
can still find the terminal width in this situation.

Previously, we'd always use a width of 80 when invoked by git.

terminal_size discussion:
https://github.com/eminence/terminal-size/issues/23

term_size does claim to support Windows, and #71 was not fixed by
changing libraries, so this seems reasonable.

Cargo.lock

@@ -171,7 +171,7 @@ dependencies = [
  "regex",
  "rustc-hash",
  "strsim 0.10.0",
- "terminal_size",
+ "term_size",
  "tree-sitter",
  "typed-arena",
  "walkdir",
@@ -435,22 +435,22 @@ dependencies = [
 ]
 
 [[package]]
-name = "termcolor"
-version = "1.1.2"
+name = "term_size"
+version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2dfed899f0eb03f32ee8c6a0aabdb8a7949659e3466561fc0adf54e26d88c5f4"
+checksum = "1e4129646ca0ed8f45d09b929036bafad5377103edd06e50bf574b353d2b08d9"
 dependencies = [
- "winapi-util",
+ "libc",
+ "winapi",
 ]
 
 [[package]]
-name = "terminal_size"
-version = "0.1.17"
+name = "termcolor"
+version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "633c1a546cee861a1a6d0dc69ebeca693bf4296661ba7852b9d21d159e0506df"
+checksum = "2dfed899f0eb03f32ee8c6a0aabdb8a7949659e3466561fc0adf54e26d88c5f4"
 dependencies = [
- "libc",
- "winapi",
+ "winapi-util",
 ]
 
 [[package]]

Cargo.toml

@@ -38,7 +38,7 @@ pretty_env_logger = "0.4.0"
 mimalloc = { version = "0.1.26", default-features = false }
 radix-heap = "0.4.1"
 walkdir = "2.3.2"
-terminal_size = "0.1.17"
+term_size = "0.3.2"
 
 [dev-dependencies]
 pretty_assertions = "1.0.0"
@@ -58,3 +58,5 @@ debug = false
 [[bin]]
 name = "difft"
 path = "src/main.rs"
+
+[features]

src/side_by_side.rs

@@ -6,7 +6,6 @@ use std::{
     collections::{HashMap, HashSet},
     env,
 };
-use terminal_size::terminal_size;
 
 use crate::{
     context::opposite_positions,
@@ -29,7 +28,7 @@ fn display_width() -> usize {
         }
     }
 
-    terminal_size().map(|(w, _)| w.0 as usize).unwrap_or(80)
+    term_size::dimensions().map(|(w, _)| w).unwrap_or(80)
 }
 
 /// Split `s` by newlines, but guarantees that the output is nonempty.