Version 2.1 beta 9

Beta version of baco 2.1.
Now every backup gets its own checksum file (*.sha1.gz). Identically files can be found and linked with help of checksums. Version 2 of baco is compatible with old version.
New configuration keywords "take" and "omit" allow including and excluding files and folders without regular expressions but with wildcards.
This is the last version for .NET Framework 4.0.