Add IncSearch highlighting. Fixes #6.

colors/onedark.vim

@@ -151,7 +151,7 @@ call s:h("VertSplit", { "fg": s:vertsplit }) " the column separating vertically
 call s:h("Folded", {}) " line used for closed folds
 call s:h("FoldColumn", {}) " 'foldcolumn'
 call s:h("SignColumn", {}) " column where signs are displayed
-call s:h("IncSearch", {}) " 'incsearch' highlighting; also used for the text replaced with ":s///c"
+call s:h("IncSearch", { "fg": s:visual_black, "bg": s:visual_grey }) " 'incsearch' highlighting; also used for the text replaced with ":s///c"
 call s:h("LineNr", { "fg": s:gutter_fg_grey, "bg": s:gutter_bg_grey }) " Line number for ":number" and ":#" commands, and when 'number' or 'relativenumber' option is set.
 call s:h("CursorLineNr", {}) " Like LineNr when 'cursorline' or 'relativenumber' is set for the cursor line.
 call s:h("MatchParen", {}) " The character under the cursor or just before it, if it is a paired bracket, and its match.