#9 inconsistent color codes are generated (patch attached)

[Erik Sigra]

The output contains inconsistent color codes.
Sometimes they have a #, sometimes not. Sometimes
hexadecimal digits are lowercase, sometimes not. This
patch fixes it. To verify that there are no uppercase
hexadecimal digits left after applying the patch,
execute this command:

grep -E "(color|link)=\"#[0123456789abcdefABCDEF]{0,5}
[ABCDEF][0123456789abcdefABCDEF]{0,5}\">" code2html

[Erik Sigra]

patch to fix the bug