Remove leftover from the demos

Was missed in c7d45ec085.

demos/plugins/custom_import_plugin/import_plugin.gd

@@ -1,84 +0,0 @@
-tool
-
-extends EditorImportPlugin
-
-
-# Simple plugin that imports a text file with extension .mtxt
-# which contains 3 integers in format R,G,B (0-255)
-# (see example .mtxt in this folder)
-# Imported file is converted to a material
-
-var dialog = null
-
-func get_name():
-	return "silly_material"
-
-func get_visible_name():
-	return "Silly Material"
-
-func import_dialog(path):
-	var md = null
-	if (path!=""):
-		md = ResourceLoader.load_import_metadata(path)
-	dialog.configure(self,path,md)
-	dialog.popup_centered()
-
-func import(path,metadata):
-
-	assert(metadata.get_source_count() == 1)
-
-	var source = metadata.get_source_path(0)
-	var use_red_anyway = metadata.get_option("use_red_anyway")
-
-	var f = File.new()
-	var err = f.open(source,File.READ)
-	if (err!=OK):
-		return ERR_CANT_OPEN
-
-	var l = f.get_line()
-
-	f.close()
-
-	var channels = l.split(",")
-	if (channels.size()!=3):
-		return ERR_PARSE_ERROR
-
-	var color = Color8(int(channels[0]),int(channels[1]),int(channels[2]))
-
-	var material
-
-	if (ResourceLoader.has(path)):
-		# Material is in use, update it
-		material = ResourceLoader.load(path)
-	else:
-		# Material not in use, create
-		material = FixedMaterial.new()
-
-	if (use_red_anyway):
-		color=Color8(255,0,0)
-
-	material.set_parameter(FixedMaterial.PARAM_DIFFUSE,color)
-
-	# Make sure import metadata links to this plugin
-
-	metadata.set_editor("silly_material")
-
-	# Update the md5 value of the source file
-
-	metadata.set_source_md5(0, f.get_md5(source))
-
-	# Update the import metadata
-
-	material.set_import_metadata(metadata)
-
-
-	# Save
-	err = ResourceSaver.save(path,material)
-
-	return err
-
-
-func config(base_control):
-
-	dialog = preload("res://addons/custom_import_plugin/material_dialog.tscn").instance()
-	base_control.add_child(dialog)