Added ex mode to line editor, a 'keymap' builtin, and a zsh-like widget system using ':!<shellcmd>' ex mode commands

Cargo.toml

@@ -2,7 +2,7 @@
 name = "shed"
 description = "A linux shell written in rust"
 publish = false
-version = "0.4.0"
+version = "0.5.0"
 
 edition = "2024"
 
@@ -15,6 +15,7 @@ bitflags = "2.8.0"
 clap = { version = "4.5.38", features = ["derive"] }
 env_logger = "0.11.9"
 glob = "0.3.2"
+itertools = "0.14.0"
 log = "0.4.29"
 nix = { version = "0.29.0", features = ["uio", "term", "user", "hostname", "fs", "default", "signal", "process", "event", "ioctl", "poll"] }
 rand = "0.10.0"