Fix config.rb to File.expand_path $include path in inputrc (#592)

* Fix config.rb to File.expand_path $include path in inputrc

* fix bug of test_include_expand_path on Windows

Author: elfham

lib/reline/config.rb

@@ -252,7 +252,7 @@ def handle_directive(directive, file, no)
       end
       @skip_section = @if_stack.pop
     when 'include'
-      read(args)
+      read(File.expand_path(args))
     end
   end
 

test/reline/test_config.rb

@@ -160,6 +160,23 @@ def test_include
     assert_equal :audible, @config.instance_variable_get(:@bell_style)
   end
 
+  def test_include_expand_path
+    home_backup = ENV['HOME']
+    File.open('included_partial', 'wt') do |f|
+      f.write(<<~PARTIAL_LINES)
+        set bell-style on
+      PARTIAL_LINES
+    end
+    ENV['HOME'] = Dir.pwd
+    @config.read_lines(<<~LINES.lines)
+      $include ~/included_partial
+    LINES
+
+    assert_equal :audible, @config.instance_variable_get(:@bell_style)
+  ensure
+    ENV['HOME'] = home_backup
+  end
+
   def test_if
     @config.read_lines(<<~LINES.lines)
       $if Ruby