fix clap with default value option #17 (#18)

remove `required_unless_present` when with `default_value` configured.

Author: yinheli

examples/examples/broadcast/broadcast.rs

@@ -40,7 +40,6 @@ async fn main() -> Result<()> {
         )
         .arg(
             Arg::new("port")
-                .required_unless_present("FULLHELP")
                 .takes_value(true)
                 .default_value("8080")
                 .long("port")

examples/examples/data-channels-close/data-channels-close.rs

@@ -38,7 +38,6 @@ async fn main() -> Result<()> {
         )
         .arg(
             Arg::new("close-after")
-                .required_unless_present("FULLHELP")
                 .takes_value(true)
                 .default_value("5")
                 .long("close-after")

examples/examples/offer-answer/answer.rs

@@ -202,15 +202,13 @@ async fn main() -> Result<()> {
         )
         .arg(
             Arg::new("offer-address")
-                .required_unless_present("FULLHELP")
                 .takes_value(true)
                 .default_value("localhost:50000")
                 .long("offer-address")
                 .help("Address that the Offer HTTP server is hosted on."),
         )
         .arg(
             Arg::new("answer-address")
-                .required_unless_present("FULLHELP")
                 .takes_value(true)
                 .default_value("0.0.0.0:60000")
                 .long("answer-address")

examples/examples/offer-answer/offer.rs

@@ -160,15 +160,13 @@ async fn main() -> Result<()> {
         )
         .arg(
             Arg::new("offer-address")
-                .required_unless_present("FULLHELP")
                 .takes_value(true)
                 .default_value("0.0.0.0:50000")
                 .long("offer-address")
                 .help("Address that the Offer HTTP server is hosted on."),
         )
         .arg(
             Arg::new("answer-address")
-                .required_unless_present("FULLHELP")
                 .takes_value(true)
                 .default_value("localhost:60000")
                 .long("answer-address")