Add help for 'show' command. Fixes #236.

main/Act.scala

@@ -10,6 +10,7 @@ package sbt
 	import DefaultParsers._
 	import Types.idFun
 	import java.net.URI
+	import CommandSupport.ShowCommand
 
 object Act
 {
@@ -153,7 +154,7 @@ object Act
 			scopedKeyParser(extracted) flatMap Aggregation.valueParser(state, structure, show)
 		}
 	}
-	def showParser = token( ("show" ~ Space) ^^^ true) ?? false
+	def showParser = token( (ShowCommand ~ Space) ^^^ true) ?? false
 	def scopedKeyParser(state: State): Parser[ScopedKey[_]] = scopedKeyParser(Project extract state)
 	def scopedKeyParser(extracted: Extracted): Parser[ScopedKey[_]] =
 	{

main/CommandSupport.scala

@@ -38,6 +38,7 @@ object CommandSupport
 	val TasksCommand = "tasks"
 	val ProjectCommand = "project"
 	val ProjectsCommand = "projects"
+	val ShowCommand = "show"
 
 	val Exit = "exit"
 	val Quit = "quit"
@@ -49,6 +50,17 @@ EvalCommand + """ <expression>
 	Evaluates the given Scala expression and prints the result and type.
 """
 
+	def actHelp = Help(ShowCommand, (ShowCommand + " <key>", actBrief), actDetailed)
+	def actBrief = "Displays the result of evaluating the setting or task associated with 'key'."
+	def actDetailed =
+ShowCommand + """ <setting>
+
+	Displays the value of the specified setting.
+
+""" + ShowCommand + """ <task>
+
+	Evaluates the specified task and display the value returned by the task."""
+
 	val LastCommand = "last"
 	val LastGrepCommand = "last-grep"
 
@@ -109,7 +121,7 @@ SetCommand + """ <setting-expression>
 	/** The command name to terminate the program.*/
 	val TerminateAction: String = Exit
 
-	def continuousBriefHelp = (ContinuousExecutePrefix + " <action>", "Executes the specified command whenever source files change.")
+	def continuousBriefHelp = (ContinuousExecutePrefix + " <command>", "Executes the specified command whenever source files change.")
 
 	def tasksPreamble = """
 This is a list of tasks defined for the current project.

main/Main.scala

@@ -391,7 +391,7 @@ object BuiltinCommands
 		for(id <- build.defined.keys.toSeq.sorted) log.info("\t" + prefix(id) + id)
 	}
 
-	def act = Command.custom(Act.actParser)
+	def act = Command.custom(Act.actParser, actHelp :: Nil)
 
 	def projects = Command.command(ProjectsCommand, projectsBrief, projectsDetailed ) { s =>
 		val extracted = Project extract s