Remove docgen.nim's dependency on things being in path

compiler/docgen.nim relied heavily on $lib/packages/docutils being in
path at compile-time. While this works fine when building Nim itself,
things start breaking when using compiler as a nimble package.

compiler/docgen.nim

@@ -13,8 +13,10 @@
 
 import
   ast, strutils, strtabs, options, msgs, os, ropes, idents,
-  wordrecg, syntaxes, renderer, lexer, rstast, rst, rstgen, times, highlite,
-  importer, sempass2, json, xmltree, cgi, typesrenderer, astalgo
+  wordrecg, syntaxes, renderer, lexer, packages/docutils/rstast,
+  packages/docutils/rst, packages/docutils/rstgen, times,
+  packages/docutils/highlite, importer, sempass2, json, xmltree, cgi,
+  typesrenderer, astalgo
 
 type
   TSections = array[TSymKind, Rope]

compiler/nim.cfg

@@ -4,8 +4,6 @@ hint[XDeclaredButNotUsed]:off
 path:"llvm"
 path:"$projectPath/.."
 
-path:"$lib/packages/docutils"
-
 define:booting
 #import:"$projectpath/testability"