converting all sources and pom.xmls to use slf4j rather than log4j
directly for more flexibility. now only elk-cli, elk-standalone and
elk-protege have runtime dependencies on log4j. i had to move
MessageDialogAppender from elk-util-logging to elk-protege to untie the
former from log4j. also, i had to re-work ELK messages slightly since
slf4j can't log structured objects, instead it provides markers which
aren't yet implemented by log4j (we need to wait till log4j 2.0 is out
of beta). finally, elk-protege's pom.xml changed to include slf4j in the
bundle so the plugin can be properly loaded into OSGI.
adding slf4j to pom + minor tweaks
using parameterized logging in slf4j
replacing Logger.isTraceEnabled() and the like by the parameterized
logging. not touching any cases where isTraceEnabled encloses any method
calls since we don't want any overhead if tracing isn't enabled.
Merge master into elk-parent-datatypes