ADD: Smart extract option (issue #3)

src/fextractdlg.lfm

@@ -143,6 +143,7 @@ inherited frmExtractDlg: TfrmExtractDlg
         Height = 26
         Top = 6
         Width = 446
+        AllowGrayed = True
         BorderSpacing.Top = 2
         Caption = 'Unpack each archive to a &separate subdir (name of the archive)'
         TabOrder = 0

src/fextractdlg.pas

@@ -278,6 +278,12 @@ begin
           // Set operation specific options
           if Assigned(Operation) then
           begin
+            if cbInSeparateFolder.State = cbGrayed then
+            begin
+              with Operation as TArchiveCopyOutOperation do
+                ExtractFlags:= ExtractFlags + [efSmartExtract];
+            end;
+
             if ArchiveFileSource.IsInterface(IMultiArchiveFileSource) then
             begin
               with Operation as TMultiArchiveCopyOutOperation do