various improvements

[gsar]

Introduces the following changes:

• ignores noscript tags in html

• treats unicode \u00a0 and similar as whitespace when considering space characters for various operations

• ignores whitespace when avoiding duplicate urls in the output

• adds a :show_links option to suppress outputting links (default behavior remains unchanged)

I will add tests if these changes seem acceptable.

[bdurand]

Those changes sound reasonable. Go ahead and add the tests.