Remove MainResult and MainError

Since we have the [#cmd_lib::main] attr macro, we don't need them any
more.

examples/dd_test.rs

@@ -34,7 +34,7 @@ struct Opt {
 }
 
 #[cmd_lib::main]
-fn main() -> MainResult {
+fn main() -> CmdResult {
     let Opt {
         block_size,
         thread_num,

examples/pipes.rs

@@ -339,7 +339,7 @@ fn rand() -> i32 {
 }
 
 #[cmd_lib::main]
-fn main() -> MainResult {
+fn main() -> CmdResult {
     // simple pre-check of TERM, tput's error message should be enough
     let term = std::env::var("TERM").unwrap();
     run_cmd!(tput -T $term sgr0 >/dev/null)?;

examples/rust_cookbook.rs

@@ -6,7 +6,7 @@ use cmd_lib::*;
 use std::io::{BufRead, BufReader};
 
 #[cmd_lib::main]
-fn main() -> MainResult {
+fn main() -> CmdResult {
     cmd_lib::set_pipefail(false); // do not fail due to pipe errors
 
     // Run an external command and process stdout

examples/tetris.rs

@@ -557,7 +557,7 @@ fn cmd_exit() {
 }
 
 #[cmd_lib::main]
-fn main() -> MainResult {
+fn main() -> CmdResult {
     #[rustfmt::skip]
     let old_cfg = run_fun!(stty -g)?; // let's save terminal state ...
     tls_set!(old_stty_cfg, |cfg| *cfg = old_cfg);

macros/src/lib.rs

@@ -8,7 +8,7 @@ use quote::quote;
 /// # use cmd_lib::*;
 ///
 /// #[cmd_lib::main]
-/// fn main() -> MainResult {
+/// fn main() -> CmdResult {
 ///     run_cmd!(bad_cmd)?;
 ///     Ok(())
 /// }

src/lib.rs

@@ -383,16 +383,12 @@ pub use log as inner_log;
 #[doc(hidden)]
 pub use logger::try_init_default_logger;
 #[doc(hidden)]
-pub use main_error::MainError;
-pub use main_error::MainResult;
-#[doc(hidden)]
 pub use process::{register_cmd, AsOsStr, Cmd, CmdString, Cmds, GroupCmds, Redirect};
 pub use process::{set_debug, set_pipefail, CmdEnv};
 
 mod builtins;
 mod child;
 mod io;
 mod logger;
-mod main_error;
 mod process;
 mod thread_local;