Merge pull request NLog#1646 from bhaeussermann/branch1

FileTarget: Fix file archive race-condition.

update dependency for NLog.Config

FileTarget: Performance improvement for CleanupInvalidFileNameChars (N…

…Log#1582)

* FileTarget: Performance improvement for CleanupInvalidFileNameChars

* Added unit test

Update changelog

Merge pull request NLog#1504 from NLog/fix-movenext-for-asyncmethods-…

…with-return-value

Fix ${callsite} with async method with return value

Merge pull request NLog#1456 from bhaeussermann/branch0

FileTarget: Fix premature termination of appender-invalidator-thread.

Merge pull request NLog#1411 from NLog/improve-mail-from-property

MailTarget: fix "From" errors (bug introduced in NLog 4.3.2)

Merge pull request NLog#1404 from NLog/filetarget-thread-background

FileTarget cleanup: move to background thread.

Merge pull request NLog#1386 from NLog/fix-InitializeTarget-exception

Fix "allLayouts is null" exception

Merge pull request NLog#1211 from NLog/nlogconfig-4.3

Update nlog.config for 4.3