New features

• Support <img> rendered as ![]()
• Resize image(set the width attribute of img, change ![]() into img if it not inline html image)
• Toggle inline image and block image.(if image has align attribute, it's block image, others are inline image)
• Show title bellow image if it's block image.

This change is 

Existed bugs:

• backspace in title input will cause error.
• No need to reupload image when modify alt and title.
• The transformer dots is still shown when the image is deleted.
• Show loading status when the image is loading from internet.
• Open a file with images, click one image in the file, the transformer dots are not shown at the first time.