Add --custom-html-attrs option to support custom HTML tags and attributes

[Lyubomyr Shaydariv]

Hi,

Some HTML documents use non-standard attributes that are essentially URLs that 
might be walked through. The attached patch allows to specify new tags and 
attributes to follow.

Example of use:

./wget -nd -r -P . -A jpg \
    --custom-html-attrs=div/big_img,div/med_img \
    http://localhost/index.html

However:
The patch does not include tests or external documentation updates of any kind. 
It does not validate tag/attribute pairs except of simple "/" checking. 
I'm not a C programmer, so I'm fine if the patch is considered poor and 
consequently rejected.
Thanks.

0001-Add-custom-html-attrs-option-to-support-custom-HTML-.patch
Description: Source code patch