Change colors and create menu in the header

Begin sketching redesign based on http://imgur.com/a/y1dHo .

This commit changes the colors of the index page to match and adds the
menu items and the css to make the header look decent from many sizes.
Finish off most of sketch for the index page
Create sketch for type.html page
Add sub-menu on types page
Fix sub-menu links
Start getting handling in place for updated header

This includes setting up the menu and sub-menus, though it currently
only displays a selection on the top menu
Use new, simpler index page

Doesn't do anything with actual indices though
Add indices for the language, type, and routine sections
Merge branch 'master' into redesign
Make selected menu-item more distinct
Move type docs to lib/Type and lang docs to lib/Language

(htmlify.p6 is not yet updated for this change)
Adjust htmlify.p6 to account for moved docs

Still needs some abstracting to deal with the hypothetical lib/Routine
and lib/Module dirs, but this works fine for now
Get rid of superstitious .[0]
Move search label inside search box
Get rid of space between selected menu item and sub-menu
Realize that index.html isn't being generated properly

The really correct way to do it is to turn index.html into an index.pod
and find some place to put it
Add TODO file
Detect multiple subkinds on routines + note if a subkind can't be found

This is useful for those routines defined as both a sub and method, of
which Perl 6 has many
Update handling of the now listy Documentable.subkind
Rename .subkind to .subkinds