Enable date based archiving.
archiveNumbering can be set to Date.
archiveFileName should contain the standard {#} placeholder for numbers which will now be used to store the archive date.
archiveDateFormat can optionally be specified for a custom date format.
maxArchiveFiles will be honored and old files deleted when applicable (based on archive period)
Merge pull request #241 from mkaltner/master

Date Based File Archiving
Fixed SL5 compilation error
Merge pull request #257 from emazv72/master

Fixed SL5 compilation error
Fix build error in .NET 2.0

.NET 2.0 doesn't support optional parameters on older compilers
NLog.Config should not include NLog.xsd

It should instead depend on NLog.Schema
fixes #258
Merge branch 'master' into CodeBetterBuildServer

Conflicts:
	src/NLog/Targets/FileTarget.cs