Use Log4j 2 for logging

This removes the POILogger and POILogFactory mechanism for logging. This mechanism was created at a time when the Java landscape looked very different than it does today.

Log4j 2 is an Apache Foundation project that is well maintained and is widely regarded as having good performance and capabilities. We use only the Log4j API artifact. This lets application developers choose how they want to capture logging events if at all. Integrations with Log4j 2 Core and Logback are available from the Log4j project.

git-svn-id: https://svn.apache.org/repos/asf/poi/branches/log4j@1886103 13f79535-47bb-0310-9956-ffa450edef68
285 files changed