Add several comments for localizers in Bundle.properties

src/org/omegat/Bundle.properties

@@ -246,23 +246,26 @@ ENCODING_AUTO=<auto>
 
 
 # MainWindow
+# Info shown in the Editor pane when project contains no [supported] source files
 TF_INTRO_EMPTYPROJECT=You project does not seem to contain translatable files.\n\n\
 To add files to the project you can:\n\n\
 \t- drag and drop files on this pane,\n\
 \t- use Project > Add Files...,\n\
 \t- use Project > Source Files... and click on Add Files...\n\
 \t- or use your file manager to copy files to the \'source\' folder,\n\
-\t   and then use Project > Reload to reload the project.\n\n\
+\t  and then use Project > Reload to reload the project.\n\n\
 If the project contains files but their content is not displayed here:\n\n\
 \t- use Options > File Filters... to verify that their format is supported by OmegaT,\n\
 \t- open them in their original application and verify that they are not empty.
 
+# Editor pane title when there are no supported source files
 TF_INTRO_EMPTYPROJECT_FILENAME=The project is empty
 
 TF_WARNING=Warning
 
 TF_ERROR=Error
 
+# This message is supposed to be printed out to stdout (not in GUI)
 TF_CHOSEN_YES=OmegaT automatically chose the 'Yes' option.
 
 # PROJECT MENU