std: fold into embassy core, add non-hacky time driver.

examples/std/src/bin/net.rs

@@ -2,11 +2,10 @@
 #![allow(incomplete_features)]
 
 use clap::{AppSettings, Clap};
-use embassy::executor::Spawner;
+use embassy::executor::{Executor, Spawner};
 use embassy::io::AsyncWriteExt;
 use embassy::util::Forever;
 use embassy_net::*;
-use embassy_std::Executor;
 use heapless::Vec;
 use log::*;
 

examples/std/src/bin/serial.rs

@@ -5,9 +5,9 @@
 mod serial_port;
 
 use async_io::Async;
+use embassy::executor::Executor;
 use embassy::io::AsyncBufReadExt;
 use embassy::util::Forever;
-use embassy_std::Executor;
 use log::*;
 use nix::sys::termios;
 

examples/std/src/bin/tick.rs

@@ -1,9 +1,9 @@
 #![feature(type_alias_impl_trait)]
 #![allow(incomplete_features)]
 
+use embassy::executor::Executor;
 use embassy::time::{Duration, Timer};
 use embassy::util::Forever;
-use embassy_std::Executor;
 use log::*;
 
 #[embassy::task]