feat: contexts support

examples/command_with_timeout.v

@@ -0,0 +1,27 @@
+import context
+import runcmd
+import time
+
+fn main() {
+	// Create context with cancel.
+	mut bg := context.background()
+	mut ctx, _ := context.with_timeout(mut bg, 10 * time.second)
+
+	// Create new command with context.
+	mut cmd := runcmd.with_context(ctx, 'sleep', '120')
+
+	// Start a command.
+	started := time.now()
+	println('Start command at ${started}')
+	cmd.start()!
+
+	// Wait for command.
+	cmd.wait()!
+
+	// The `sleep 120` command would run for two minutes without a timeout.
+	// But in this example, it will time out after 10 seconds.
+	println('Command finished after ${time.now() - started}')
+
+	// Since command has been terminated, the state would be: `signal: 15 (SIGTERM)`
+	println('Child state: ${cmd.state}')
+}