Update packages to latest versions:

This commit updates several packages to their latest versions
- unicode-width
- nix
- jwalk
- tui
- crosterm

And fixes some code to use the API of the latest packages

Cargo.toml

@@ -10,14 +10,14 @@ license = "MIT"
 edition = "2018"
 
 [dependencies]
-tui = {version="0.11", default-features = false, features = ['crossterm'] }
-crossterm = "0.17"
+tui = {version="0.19", default-features = false, features = ['crossterm'] }
+crossterm = "0.29"
 failure = "0.1"
-jwalk = "0.5"
+jwalk = "0.8"
 structopt = "0.3"
 filesize = "0.2.0"
-unicode-width = "0.1.7"
-nix = "0.17.0"
+unicode-width = "0.2.2"
+nix = { version = "0.30.0", features = ["user"] }
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3", features = ["securitybaseapi","debugapi"] }