op_texture_reload_all.py

import bpy
import os
import bmesh
from mathutils import Vector
from collections import defaultdict
from math import pi

class op(bpy.types.Operator):
	bl_idname = "uv.textools_texture_reload_all"
	bl_label = "Reload Textures and remove unused Textures"
	bl_description = "Reload all textures"

	@classmethod
	def poll(cls, context):
		return True

	def execute(self, context):
		main(context)
		return {'FINISHED'}


def main(context):
	count_clear_mat = 0
	count_clear_img = 0
	count_reload = 0

	for material in bpy.data.materials:
		if not material.users:
			count_clear_mat+=1
			material.user_clear()
			bpy.data.materials.remove(material)

	# Clean up unused images
	for image in bpy.data.images:
		if not image.users:
			count_clear_img+=1
			image.user_clear()
			bpy.data.images.remove(image)

	#Reload all File images
	for img in bpy.data.images :
		if img.source == 'FILE' :
			count_reload+=1
			img.reload()

	# Refresh vieport texture
	for window in bpy.context.window_manager.windows:
		screen = window.screen
		for area in screen.areas:
			area.tag_redraw()

	# Show popup on cleared & reloaded items
	message = ""
	if count_reload > 0:
		message+="{}x reloaded. ".format(count_reload)
	if count_clear_mat > 0:
		message+="{}x mat cleared. ".format(count_clear_mat)
	if count_clear_img > 0:
		message+="{}x img cleared.".format(count_clear_img)

	if len(message) > 0:
		bpy.ops.ui.textools_popup('INVOKE_DEFAULT', message=message)
	
bpy.utils.register_class(op)