Add a --style=default option

[IsaacHorvath]

Hello, this is my first contribution, meant to resolve #2061. I added a new --style=default option that is effectively a carbon copy of --style=full, only I've taken out the file size in the header. I expect there to be more differences going forward, e.g. after implementing some of #1701.

I added a simple integration test that seems to pass okay, and updated the shell completions (though I only use bash so I haven't tested them).

I am brand spanking new to Rust, so apologies if I'm way out of line here. I'm hoping to try my hand at contributing a bit here and there to bat help practice.

[Enselic]

Thanks a lot for working on this! I took a look and couldn't find anything worth commenting on (except some nitpick in CHANGELOG). This looks great on first sight. Especially thanks for adding an integration test. Those are super great to have.

Before I set Approved I think I would like to find the time to play around a bit with the implementation too, but code-wise I see no problems so far. So I think I will be able to set this as Approved within max a week or so.

[IsaacHorvath]

Thanks for your feedback! I polished it up a bit, and I have a little more courage to snoop around the issues list now.

[Enselic]

Sorry for the delay, but I got some other things I need to take care of, and I got less spare time than I anticipated, so it might take some time still until I can take a second look.

[Enselic]

Shouldn't the file size be omitted by default with this PR? It does not seem to be the case when I try:

/Users/martin/src/bat
1166d6c Update help text for '--style'  2119  
% cargo run -- --no-config examples/simple.rs 
    Finished dev [unoptimized + debuginfo] target(s) in 0.20s
     Running `target/debug/bat --no-config examples/simple.rs`
───────┬───────────────────────────────────────────────────────────────────────────────────────────────────────────
       │ File: examples/simple.rs
       │ Size: 177 B
───────┼───────────────────────────────────────────────────────────────────────────────────────────────────────────
   1   │ /// A simple program that prints its own source code using the bat library
   2   │ use bat::PrettyPrinter;
   3   │ 
   4   │ fn main() {
   5   │     PrettyPrinter::new().input_file(file!()).print().unwrap();
   6   │ }
───────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────

Again, big thanks for working on this, and sorry for not taking a second look sooner, but my last two weeks have been unusually busy.

[IsaacHorvath]

Of course, I forgot to actually make it the default option 😅 Should be fixed now.

[Enselic]

This now seems to work as it should:

% cargo run -- --no-config examples/simple.rs       
   Compiling bat v0.20.0 (/Users/martin/src/bat)
    Finished dev [unoptimized + debuginfo] target(s) in 3.45s
     Running `target/debug/bat --no-config examples/simple.rs`
───────┬───────────────────────────────────────────────────────────────────────────────────────────────────────────
       │ File: examples/simple.rs
───────┼───────────────────────────────────────────────────────────────────────────────────────────────────────────
   1   │ /// A simple program that prints its own source code using the bat library
   2   │ use bat::PrettyPrinter;
   3   │ 
   4   │ fn main() {
   5   │     PrettyPrinter::new().input_file(file!()).print().unwrap();
   6   │ }
───────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────
% cargo run -- --no-config examples/simple.rs --style=full
    Finished dev [unoptimized + debuginfo] target(s) in 0.30s
     Running `target/debug/bat --no-config examples/simple.rs --style=full`
───────┬───────────────────────────────────────────────────────────────────────────────────────────────────────────
       │ File: examples/simple.rs
       │ Size: 177 B
───────┼───────────────────────────────────────────────────────────────────────────────────────────────────────────
   1   │ /// A simple program that prints its own source code using the bat library
   2   │ use bat::PrettyPrinter;
   3   │ 
   4   │ fn main() {
   5   │     PrettyPrinter::new().input_file(file!()).print().unwrap();
   6   │ }
───────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────
% cargo run -- --no-config examples/simple.rs --style=numbers,grid
    Finished dev [unoptimized + debuginfo] target(s) in 0.20s
     Running `target/debug/bat --no-config examples/simple.rs --style=numbers,grid`
─────┬─────────────────────────────────────────────────────────────────────────────────────────────────────────────
   1 │ /// A simple program that prints its own source code using the bat library
   2 │ use bat::PrettyPrinter;
   3 │ 
   4 │ fn main() {
   5 │     PrettyPrinter::new().input_file(file!()).print().unwrap();
   6 │ }
─────┴─────────────────────────────────────────────────────────────────────────────────────────────────────────────

I left some additional comments that would be good to respond to, but apart from that I consider this Approved now. Good job and thanks again!

[Enselic]

Approved without reservation. Thank you for the updates.

[sharkdp]

Thank you for your contribution. I think this part of help text needs updating:

 * auto: same as 'full', unless the output is piped.

I guess this is now: "same as 'default', unless …".

Also, it would be great if the man page (template) in assets/manual/bat.1.in could be updated accordingly.

[IsaacHorvath]

I did already update the --style section of the manpage with:
Possible values: *default*, full, auto, plain, changes, header, header-filename, header-filesize, grid, rule, numbers, snip.
Is there something I missed?

I'll add the help text change now.

[Enselic]

Looks to me like @sharkdp's comments have been taken care of. Let's merge this now. Thanks again.