[refactoring] remove unused imports in the compiler and in some stdlib modules

compiler/main.nim

@@ -13,12 +13,12 @@ when not defined(nimcore):
   {.error: "nimcore MUST be defined for Nim's core tooling".}
 
 import
-  llstream, strutils, ast, astalgo, lexer, syntaxes, renderer, options, msgs,
-  os, condsyms, times,
-  wordrecg, sem, semdata, idents, passes, extccomp,
+  llstream, strutils, ast, lexer, syntaxes, options, msgs,
+  condsyms, times,
+  sem, idents, passes, extccomp,
   cgen, json, nversion,
-  platform, nimconf, importer, passaux, depends, vm, vmdef, types, idgen,
-  parser, modules, ccgutils, sigmatch, ropes,
+  platform, nimconf, passaux, depends, vm, idgen,
+  parser, modules,
   modulegraphs, tables, rod, lineinfos, pathutils
 
 when not defined(leanCompiler):