Converted into External Plugin, simplified image size check, removed image/media/link plugin dependancies.

• This plugin can now run outside of the tinyMCE install plugins folder. Makes updating tinyMCE, and this plugin, easier.
• Did away with customized Image, Media, and Link plugins. Makes updating tinyMCE, and this plugin, easier.
• Offloaded figuring out the image size to tinyMCE's built-in functions.
• Removed console.log() lines
• Apparently Windows PHP wants paths in $current_path (in config.php) as \, so I added a line to convert that back to /.