Implemented Logger.Swallow and Logger.SwallowAsync methods
Fix for x64 NLog.LoggerImpl.Write callsite
Fixes empty "properties" collection.

When using an event-context variable, the properties collection was
empty, even when property items where explicitly given. This function
fixes this.
Removed comment
Added a helper class for handling invalid XML characters (used in Log4JXmlEventLayoutRenderer)
Merge pull request #336 from JvanderStad/fix/invalid-characters-in-xml

Fix for invalid XML characters in Log4JXmlEventLayoutRenderer
Merge pull request #334 from erwinwolff/master

Fixes empty "properties" collection.
Merge pull request #335 from JvanderStad/fix/callsite-incorrect

Fix/callsite incorrect
Merge branch 'master' of github.com:robertvazan/NLogSwallow into NLogSwallow

Conflicts:
	src/NLog/Logger.cs
	tests/NLog.UnitTests/LoggerTests.cs
	tests/NLog.UnitTests/NLogTestBase.cs
Merge branch 'NLogSwallow' into umaster