Proposal: fix for Parser returning empty imports

The fix is quite naive and has not been tested. It works with compiler but it hasn't been tried with web handler.

src/dotless.Compiler/Program.cs

@@ -100,6 +100,7 @@ private static IEnumerable<string> CompileImpl(ILessEngine engine, string inputF
                 files.Add(inputFilePath);
                 foreach (var file in engine.GetImports())
                     files.Add(Path.Combine(directoryPath, Path.ChangeExtension(file, "less")));
+                engine.ResetImports();
                 return files;
             }
             catch (IOException)

src/dotless.Core/Engine/CacheDecorator.cs

@@ -54,5 +54,10 @@ public IEnumerable<string> GetImports()
         {
             return Underlying.GetImports();
         }
+
+        public void ResetImports()
+        {
+            Underlying.ResetImports();
+        }
     }
 }

src/dotless.Core/Engine/ILessEngine.cs

@@ -5,6 +5,7 @@ namespace dotless.Core
     public interface ILessEngine
     {
         string TransformToCss(string source, string fileName);
+        void ResetImports();
         IEnumerable<string> GetImports();
     }
 }

src/dotless.Core/Engine/LessEngine.cs

@@ -54,5 +54,11 @@ public IEnumerable<string> GetImports()
         {
             return Parser.Importer.Imports.Distinct();
         }
+
+        public void ResetImports()
+        {
+            Parser.Importer.Imports.Clear();
+        }
+
     }
 }

src/dotless.Core/Engine/ParameterDecorator.cs

@@ -31,5 +31,10 @@ public IEnumerable<string> GetImports()
         {
             return Underlying.GetImports();
         }
+
+        public void ResetImports()
+        {
+            Underlying.ResetImports();
+        }
     }
 }

src/dotless.Core/Parser/Parser.cs

@@ -86,7 +86,7 @@ public Parser(int optimization, IStylizer stylizer, Importer importer)
 
         public Ruleset Parse(string input, string fileName)
         {
-            Importer.Imports = new List<string>();
+            Tokenizer.SetupInput(input);
             ParsingException parsingException = null;
             Ruleset root = null;