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.