Use empty strings in case the decryption failed.

git-svn-id: http://tortoisesvn.googlecode.com/svn/trunk@25908 4cfb86a4-2c7a-11df-bd14-c1e331e6ceac
Encrypt the string to a single-line-string to avoid problems when storing it in an ini file.

git-svn-id: http://tortoisesvn.googlecode.com/svn/trunk@25909 4cfb86a4-2c7a-11df-bd14-c1e331e6ceac
Replace _T() with L""

git-svn-id: http://tortoisesvn.googlecode.com/svn/trunk@25910 4cfb86a4-2c7a-11df-bd14-c1e331e6ceac