This plug-in highlights characters such as non breakable space, characters that often break compilers and scripts and is almost impossible to spot in the editor.
Clone the repository and copy the whole project directory into the Packages folder, you can open your sublime packages with a menu option Sublime Text -> Preferences -> Browse Packages...
You can override the following parameters within your file settings:
highlight_unicode_max_file_size: Restrict this to a sane size in order not to DDOS your editor. Defaults to 1048576 (1 Mio).
highlight_unicode_color_name: Change this to a valid scope name, which has to be defined within your theme. Defaults to 'invalid'.