[Unit Testing] More variadic placeholder checking.

Modified test, that checks proper attributes formatting via string formatter. Variadic placeholder should include both global and external attributes and must not contain internal one, like timestamp, verbosity or message.
[Unit Testing] Refactoring.
[Unit Testing] Bug checking functional test.

Added test, that checks improper attribute set scope routing.
[Bug Fix] Fixed improper attributes routing.

Accidentally all wrapper-attached attributes were routed to the internal section, which contain only internal attributes, like timestamp, severity or message.

Internal attributes are not shown in variadic placeholders, but all user-defined attributes should.

This commit fixes and tests that bug.
[Version] Bumped.
[Synchronizing] With branch 'v0.3'.