Removed clang tests because travis removed support for clang apt

Use CMake Threads package instead of manually specifying -pthread.

Create a logger with a single sink

Fix throwing exception if DYNAMIC_TIME_ZONE_INFORMATION fails

RFC: Support custom eol style

By default use the platform convention (i.e. "\r\n" on windows), but
make it possible to set a custom end-of-line string without implementing
a custom formatter.

In async mode, teardown callback on worker thread exit

(Note: this can be helpful when a custom sink invokes a JNI callback, which implies that worker thread was previously attached to JVM, and needs to be cleanly detached upon exit)

Revert "CMake script improvements"

CMake script improvements

It's no longer a standalone cmake file because cmake was crashing when
reading it as part of the subproject.