Highlight some of the default highlight groups

Firstly, an error has been corrected in the utility function named
hsv2rgb.

Secondly, some of the more useful highlight groups have been processed,
but everything may still change.

colors/odyssey.vim

@@ -17,6 +17,7 @@
 "
 " Bootstrap {{{
 
+set termguicolors
 let s:colors = {}
 
 " }}}
@@ -52,7 +53,7 @@ function! s:hsv2hex(hue, saturation, value)
   let l:l = [float2nr(l:l[0]), float2nr(l:l[1]), float2nr(l:l[2])]
 
   let l:f = "%02x"
-  return printf(l:f, l:l[0]) . printf(l:f, l:l[0]) . printf(l:f, l:l[0])
+  return printf(l:f, l:l[0]) . printf(l:f, l:l[1]) . printf(l:f, l:l[2])
 endfunction
 
 function! s:HL(group, bg, ...)
@@ -99,5 +100,38 @@ let s:colors.constant  = s:hsv2hex(230, 45, 70)
 " associated colors. They appear in the same order than when the highlight
 " command is used.
 
+call s:HL('SpecialKey', 'background', 'warning')
+call s:HL('EndOfBuffer', 'background', 'linenumber')
+call s:HL('NonText', 'background', 'linenumber')
+call s:HL('LineNr', 'background', 'linenumber')
+call s:HL('CursorLineNr', 'cursorline', 'foreground')
+call s:HL('StatusLine', 'cursorline', 'foreground')
+call s:HL('StatusLineNC', 'beyondback', 'linenumber')
+call s:HL('VertSplit', 'beyondback', 'beyondback')
+call s:HL('Folded', 'foldedline', 'linenumber')
+call s:HL('FoldColumn', 'foldedline', 'linenumber')
+call s:HL('CursorLine', 'cursorline')
+call s:HL('ColorColumn', 'foldedline',)
+
+call s:HL('Comment', 'background', 'linenumber')
+call s:HL('Delimiter', 'background', 'foreground')
+
+call s:HL('Statement', 'background', 'keyword')
+call s:HL('Conditional', 'background', 'keyword')
+call s:HL('Identifier', 'background', 'keyword')
+call s:HL('Tag', 'background', 'warning')
+call s:HL('Special', 'background', 'warning')
+
+call s:HL('Function', 'background', 'procedure')
+
+call s:HL('Type', 'background', 'type')
+
+call s:HL('Number', 'background', 'constant')
+call s:HL('String', 'background', 'constant')
+
+call s:HL('SpecialChar', 'background', 'constant')
+call s:HL('Preproc', 'background', 'warning')
+call s:HL('Normal', 'background', 'foreground')
+
 " }}}
 " vim: foldmethod=marker