media=<print|screen|all> selector stripped from mime_mail embedded css

This comes from Mime Mail using the css print mode of the page, which may be producing b/w results. The idea is to let some color pass to that css print mode.

This issue is also reported in Foliage theme:
#443970: Mime Mail and print.css compatibility issue
A workaround is proposed.

I have completely different symptoms which stem from the same problem.

In the mimemail.module file, the template_preprocess_mimemail_message() function adds style information to the email by taking the output of drupal_get_css() and concatenating the contents of all the linked stylesheets within a single <style>...</style> tag.

Unfortunately, in doing so, mimemail is stripping the "media=" selector from each link, so that styles intended for printing are mixed with styles intended for screen display.

In my case, this resulted in my print.css stylesheet, which hides selected portions of the page for printing, also hiding certain portions of the Yahoo webmail API when their customers view my messages.

The fix is to replace each link by an embedded stylesheet, one-by-one, while retaining the "media=" selector.

I am attaching three patches, one to fix the css errors, one to fix various E_ALL warnings, and one to fix a mail_alter bug reported in #448996: Wrong implementation of hook_mail_alter().

I have also corrected some unrelated problems in the original code:

1. The test for file_exists($styles) is made before the $styles variable is defined.
2. The regex patterns should keep working if drupal_get_css() changes how it formats its output.
3. Whitespace is collapsed rather than stripped. See #448670: Spaces are removed from CSS definitions.
4. I also found it necessary to add linefeeds. Otherwise, my /usr/sbin/sendmail chokes whenever a single line exceeds 5000 characters.