#456 Update option to overwrite/erase .#-backups automatically

[Timm Ganske]

Especially when doing merge of branches where version numbers are stored there is always a conflict. Now when you want to do "Update/Get the clean copy" WinCVS always complains that the .#Backup-file can't be created because it exists.

I see 2 solutions for this:

1. When doing update an option to "automatically erase/overwrite .#-files"

2. An option to clear the .#-Files in the whole checkout

Of course these solutions could be combined