Added a regular expressions to parse image tags in HTML for the embedded
image data.
Added a regular expression to extract the whole content div tag to avoid
having to strip off the last div.

Moved processing of chips into functions.
readImagesFromAttachment extracts multiple images from matching lines.
Images are named IMAGE_FILE_NAME_ with an index appended.
Handles png and jpeg images tags at least.

Updated README to call out new features.