Trouble with input filter configuration and processing

Hi

Thanks for this very useful and well documented module.

However, I have faced a few trouble when using the input filter feature:
- the label to enter the pattern is "Shadow Colour" instead of "Input Filter Pattern"
- the sample pattern given for h1 isn't consistent with the one for h* and leads to content being truncated after the first occurrence of h1
- preg_replace and the 'e' modifier may escape quotes, then the image being generated contains backslashes when the text contained
- some patterns could be made case insensitive
- quotes in text are meaningful and shouldn't be ignored

Please find below a comprehensive patch for all these issues (the main one being related to backslashes and to the h1 pattern)

Regards