Show hint to remove old directories (svn etc.)

[kryslt]

Recently I updated fpcupdeluxe on my Ubuntu from some historic version to the latest and ran FPC/Lazarus update (stable/trunk).
I got errors caused by old stuff on disk (I kept old fpcsrc and lazarus directories on disk, there were still old svn snapshots):

ERROR: Fpcupdeluxe fatal error !
Sequencer (UserIDE): Failure running fpcupdeluxe: error executing sequence UserIDE
Sequencer (Lazarus): Failure running fpcupdeluxe: error executing sequence Lazarus
Sequencer (Default): Failure running fpcupdeluxe: error executing sequence Default

Maybe a hint should be shown to the user to remove this old stuff?

Otherwise, this installer is just SO perfect! Thank you for this huge effort!