patch 8.2.2822: MS-Windows: unnessarily loading libraries when unregistering

Problem:    MS-Windows: unnessarily loading libraries when unregistering OLE.
Solution:   Also skip loading libraries when invoked with "-unregister".  Run
            Vim for README.txt with user privileges.
diff --git a/nsis/gvim.nsi b/nsis/gvim.nsi
index 498d98d..58ed85c 100644
--- a/nsis/gvim.nsi
+++ b/nsis/gvim.nsi
@@ -119,9 +119,9 @@
 
 !define MUI_COMPONENTSPAGE_SMALLDESC
 !define MUI_LICENSEPAGE_CHECKBOX
-!define MUI_FINISHPAGE_RUN                 "$0\gvim.exe"
+!define MUI_FINISHPAGE_RUN
+!define MUI_FINISHPAGE_RUN_FUNCTION        LaunchApplication
 !define MUI_FINISHPAGE_RUN_TEXT            $(str_show_readme)
-!define MUI_FINISHPAGE_RUN_PARAMETERS      "-R $\"$0\README.txt$\""
 
 # This adds '\Vim' to the user choice automagically.  The actual value is
 # obtained below with CheckOldVim.
@@ -300,6 +300,11 @@
   Exch $0  # put $0 on top of stack, restore $0 to original value
 FunctionEnd
 
+Function LaunchApplication
+   SetOutPath $0
+   ShellExecAsUser::ShellExecAsUser "" "$0\gvim.exe" "-R $"$0\README.txt$""
+FunctionEnd
+
 ##########################################################
 Section "$(str_section_old_ver)" id_section_old_ver
 	SectionIn 1 2 3 RO