remove obsolete stuff from log.xml
start new loggin engine
remove empty/unused stuff
deperecate logging handlers addition to Logger, migrate to Handlers
add LogUtil, get more information from log event
Logger is an abstract class
separate logging api from log4j backend
always init composite appender
remove loggers cycle
name for composite appender
simplify code, remove extra class, rename
rename&move Log4jUtil to make cherry-picking commits easier
logging language calls log4j instead of our logger

Conflicts:

	languages/baseLanguage/logging/languageModels/util.mps
	languages/baseLanguage/logging/source_gen/jetbrains/mps/baseLanguage/logging/util/LoggingGenerationUtil.java
migration script for MPS Logger usages
migrate to log4j only when no mps-specific logger methods used
move Log4jUtil back
add log4j to imls
migrate logging lang usages + mps logger model usages
refactor logging package, Logger is just a wrapper on log4j, deprecate handlers and add skeleton for appenders
get rid of logging handlers