Make ResultHandlers configuration more explicit

Handle exit as a dedicated case (prevents eg 'exit' commands in scripts to make script quit)
Add an example of custom ApplicationRunner

Fixes #187
Fixes #183

Decouple ApplicationRunners

Make ThrowableResultHandler behave differently in non-interactive mode

spring-shell-standard/src/main/java/org/springframework/shell/standard/CommandValueProvider.java

@@ -36,8 +36,6 @@ public class CommandValueProvider extends ValueProviderSupport {
 
 	private final CommandRegistry commandRegistry;
 
-	@Lazy
-	@Autowired
 	public CommandValueProvider(CommandRegistry commandRegistry) {
 		this.commandRegistry = commandRegistry;
 	}

spring-shell-standard/src/main/java/org/springframework/shell/standard/StandardAPIAutoConfiguration.java

@@ -19,6 +19,7 @@ package org.springframework.shell.standard;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Lazy;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.shell.CommandRegistry;
 import org.springframework.shell.MethodTargetRegistrar;
@@ -33,7 +34,7 @@ import org.springframework.shell.ParameterResolver;
 public class StandardAPIAutoConfiguration {
 
 	@Bean
-	public ValueProvider commandValueProvider(CommandRegistry commandRegistry) {
+	public ValueProvider commandValueProvider(@Lazy CommandRegistry commandRegistry) {
 		return new CommandValueProvider(commandRegistry);
 	}