Fix some styling of the menu.

I've had some feedback that the sub menu options don't look/feel like menu
options, the user said that he didn't realize they were clickable.  To try
to fix this I've painted them the same colour as the menu options (this
provide better contrast for my testes too) and made the font size the same.
I've also added 5px of padding on all sides of each submenu's text and
enabled the same hover behaviour as the main menu options.  The latter two
changes I think help the most to show that they're clickable.

My personal testes are that grey on white is horrible.  It provides very
little contrast and I wish that companies such as Google and Apple wouldn't
do it.  And I'd rather we didn't either.

css/common.css:
    As above.
Delete HRs in menu bar.

I don't like how, after the previous style change, the hover background
on menu items extends past the HRs.  Remove the HRs and enlarge the
padding between menu items to compensate.

css/common.css:
	As above.
Fix a typo on the menu bar.

include/menubar.inc:
	Fix a typo.
Clarify licensing on web site.

The main download page simplified the licensing terms.  The separate
'license' page stated the full situation but included a full copy of
only the GPL which may be misleading.  Including both the GPL
and LGPL would be too much.

include/download.inc:
	Move the licensing statement to the top of the main download
	page.

	Link to the (text) copies of the GPL and LGPL instead of
	reproducing them inline.

download/COPYING:
download/COPYING.LIB:
	Add these files from the Mercury distribution.

download/license.php:
include/menubar.inc:
	Delete separate license page.
Replace quote on the main page.

The old text was a placeholder and would be misleading regarding
the licensing.  The new text is a slightly condensed version of
the opening line from the JICSLP '96 Workshop slides.

include/index.inc:
	As above.
Don't use all caps for News page heading.

include/news.inc:
	As above.