- Fixed all known problems with temporary files and directoroes

- Command line switches work again (/NCRC and /S)
- GetTempFileName now takes another argument as base directory (default is $TEMP)
- Message boxes work from .onGUIEnd
- Some more optimizations


git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@2739 212acab6-be3b-0410-9dea-997c60f758d6

Source/exehead/Ui.c

@@ -417,6 +417,7 @@ nextPage:
     if (g_quit_flag || m_page < 0 || m_page == g_inst_cmnheader->num_pages)
     {
       DestroyWindow(m_curwnd);
+      g_hwnd = 0;
       EndDialog(hwndDlg,m_retcode);
     }
     else