Close running FSI sessions on application shutdown

Also:
 * don't highlight the toolbar icon unless the console has really
   launched successfully

Author: rdipardo

README.md

@@ -63,7 +63,12 @@ The [FpcPipes] unit is adapted from source code believed to be in the Public Dom
 
 The F# Software Foundation logo for F# is an asset of the F# Software Foundation: <https://foundation.fsharp.org/logo>
 
+## License
+
+[MIT]
+
 [Original source code]: https://github.com/ppv/NPPFSIPlugin
+[MIT]: https://raw.githubusercontent.com/rdipardo/nppFSIPlugin/master/Copyright.txt
 [FpcPipes]: https://github.com/rdipardo/nppFSIPlugin/blob/master/Source/Plugin/Src/FpcPipes.pas
 [Lexilla]: https://github.com/ScintillaOrg/lexilla
 [Obsidian theme F# UDL]: https://gist.github.com/rdipardo/e500e0e9053e8556350802cf8ab06583

Source/Plugin/NPPFSIPlugin.lpr

@@ -97,6 +97,10 @@ procedure beNotified(msg: PSCNotification); cdecl;
     NPPN_BUFFERACTIVATED, NPPN_LANGCHANGED, NPPN_WORDSTYLESUPDATED: begin
       TLexerProperties.SetLexer;
     end;
+    NPPN_BEFORESHUTDOWN: begin
+      if Assigned(FSIHostForm) then
+        FSIHostForm.Close;
+    end;
   end;
 end;
 /// Get the custom functions defined by the plugin.
@@ -133,8 +137,9 @@ procedure ToggleFSI; cdecl;
     Exit;
   end;
 
-  SendMessage(Npp.NppData._nppHandle, NPPM_SETMENUITEMCHECK, PluginFuncs[FSI_INVOKE_CMD_ID]._cmdID, 1);
   FSIHostForm.Show;
+  if FSIHostForm.Visible then
+    SendMessage(Npp.NppData._nppHandle, NPPM_SETMENUITEMCHECK, PluginFuncs[FSI_INVOKE_CMD_ID]._cmdID, 1);
 end;
 /// <summary>
 /// Send text from NPP to FSI.