ruby-2.5-support fix. usage with rest-arguments.

ruby-2.5 does not support `String#split() {|t|}`.  splits are replaced
by `String#split().each {|t|}`.

Usage supports printing rest-arguments.  It uses the name with three dots:

  command [<argname> ...]

Sub-commands has a generic `<command> ...` or `[<command> ...]`.
The last will be used if a nil-aliases exists.

bin/example.rb

@@ -17,11 +17,11 @@ cli.cmd( :args, "Expects and prints given arguments",
 	opt( :h, '-hsth', "No long option, only short option", default: "nothing")
 
 cli.cmd( :example, "I have an example command") { STDERR.puts "This is an example" }
-cli.cmd( :help, "", aliases: [nil, '-h', '--help'], &lambda {|*args, full:|
+cli.cmd( :help, "An example for help", aliases: [nil, '-h', '--help'], &lambda {|*commands, full:|
 	if full
-		cli.help_full *args, output: STDERR
+		cli.help_full *commands, output: STDERR
 	else
-		cli.help *args, output: STDERR
+		cli.help *commands, output: STDERR
 	end
 }).
 	opt( :full, '-f', '--[no-]full', "Print all commands and sub-commands.", default: false)
@@ -40,7 +40,7 @@ cli.sub( :more, "Sub-Commands are also possible with a new cli") do |sub|
 		opt( :e, '-e', "Toggle e")
 
 	sub.sub( :deeper, "You want to have Sub-Sub-Commands?") do |sub2|
-		sub2.cmd( :help, "", aliases: [nil, '-h', '--help'], &lambda {|*args| sub2.help( *args, output: STDERR) })
+		sub2.cmd( :help, "", aliases: [nil, '-h', '--help'], &lambda {|*commands| sub2.help( *commands, output: STDERR) })
 		sub2.cmd( :last, "The last example", &lambda { STDERR.puts "The last example" })
 
 		sub2.sub( :'sub-commands', "Endless Sub-Sub- ...") do |sub3|

lib/dencli/cmd.rb

@@ -76,8 +76,16 @@ class DenCli::CMD
 			output << (o.required? ? " #{s}" : " [#{s}]")
 		end
 		if @exe.lambda?
-			required.each {|s| output << " <#{s}>" }
-			output << " [#{additional.map{|s|"<#{s}>"}.join " "}]"  unless additional.empty?
+			parameters.each do |(type, name)|
+				case type
+				when :req
+					output << " <#{name}>"
+				when :opt
+					output << " [<#{name}>]"
+				when :rest
+					output << " [<#{name}> ...]"
+				end
+			end
 		else
 			output << ' ...'
 		end
@@ -130,7 +138,7 @@ class DenCli::CMD
 		@options.map do |_, o|
 			s, l, v, y = o.short, o.long, o.val, ','
 			if l.nil?
-				s += "=#{v}"  if v
+				s += "#{v}"  if v
 				y = ' '
 			elsif s.nil?
 				l += "=#{v}"  if v

lib/dencli/sub.rb

@@ -14,8 +14,19 @@ class DenCli::Sub
 	def full_cmd() _full_cmd [] end
 	def []( k) @aliases[k] end
 
-	def usage
-		"#{full_cmd.join ' '} ..."
+	def usage output: nil
+		output ||= ''
+		_usage output
+		output
+	end
+
+	def _usage output
+		output << full_cmd.join( ' ')
+		if @aliases.has_key? nil
+			output << " [<command> ...]"
+		else
+			output << " <command> [...]"
+		end
 	end
 
 	def help n = nil, *a, output: nil
@@ -46,37 +57,39 @@ class DenCli::Sub
 		output
 	end
 
-	def self._help_commands output, subs
-		m = subs.map {|_name,c| x = c.usage.length; 25 < x ? 0 : x }.max
-		subs.each do |_name, c|
-			if 25 < c.usage.length
-				output << "% -#{m}s\n#{' ' * m} " % [c.usage]
-			else
-				output << "% -#{m}s " % [c.usage]
-			end
-			n = m+2
-			prefix = nil
-			c.description.split /\n/ do |l|
-				c = 0
-				l.split %r< > do |w|
-					if prefix
-						output << prefix
-						prefix = nil
-					end
-					wl = w.length
-					if 75 < c+wl
-						output << "\n#{' ' * n}#{w}"
-						c = n+2+wl
-					else
-						output << " #{w}"
-						c += 1 + wl
-					end
+	class <<self
+		def _help_commands output, subs
+			m = subs.map {|_name,c| x = c.usage.length; 25 < x ? 0 : x }.max
+			subs.each do |_name, c|
+				if 25 < c.usage.length
+					output << "% -#{m}s\n#{' ' * m} " % [c.usage]
+				else
+					output << "% -#{m}s " % [c.usage]
 				end
-				prefix = "\n#{' ' * n}"
+				n = m+2
+				prefix = nil
+				c.description.split( /\n/).each do |l|
+					c = 0
+					l.split( %r< >).each do |w|
+						if prefix
+							output << prefix
+							prefix = nil
+						end
+						wl = w.length
+						if 75 < c+wl
+							output << "\n#{' ' * n}#{w}"
+							c = n+2+wl
+						else
+							output << " #{w}"
+							c += 1 + wl
+						end
+					end
+					prefix = "\n#{' ' * n}"
+				end
+				output << "\n"
 			end
-			output << "\n"
+			output
 		end
-		output
 	end
 
 	def goto *a