Delete old Start Menu shortcuts when updating

Both installer and uninstaller (just in case) remove old Start Menu shortcuts if they exist, so that there are no files left behind and the transition to the new shortcut is smooth when updating.

extra/nsis/mp-installer.nsi

@@ -305,6 +305,11 @@ Section "OBS Studio" SecCore
 
 	SetOutPath "$INSTDIR\bin\64bit"
 	CreateShortCut "$SMPROGRAMS\OBS Studio.lnk" "$INSTDIR\bin\64bit\obs64.exe"
+
+	; Delete old Start Menu shortcuts if installing upon an older version
+	Delete "$SMPROGRAMS\OBS Studio\OBS Studio (64bit).lnk"
+	Delete "$SMPROGRAMS\OBS Studio\Uninstall.lnk"
+	RMDir "$SMPROGRAMS\OBS Studio"
 SectionEnd
 
 Section -FinishSection
@@ -409,7 +414,9 @@ Section "un.${APPNAME} App Files" UninstallSection1
 	SetShellVarContext all
 	Delete "$DESKTOP\OBS Studio.lnk"
 	Delete "$SMPROGRAMS\OBS Studio\OBS Studio (32bit).lnk"
+	Delete "$SMPROGRAMS\OBS Studio\Uninstall.lnk"
 	${if} ${RunningX64}
+		Delete "$SMPROGRAMS\OBS Studio\OBS Studio (64bit).lnk"
 		Delete "$SMPROGRAMS\OBS Studio.lnk"
 	${endif}
 	SetShellVarContext current