First step of the log4j to slf4j conversation

 - Automatic conversation done
 - Client setup to be working again
Merge branch 'release/2.1.13' into develop
Merge branch 'master' into develop
Updating development channel to use current snapshot versions
Merge branch 'develop' into feature/slf4j
Implemented slf4j into all projects

 - Application launches are tested
 - Building of compiler and downloader is tested and working
[Build] Removed all additional logging utilities
Merge branch 'feature/slf4j' into develop
[Downloader] Fixed working directory upon application start
[Downloader] Skipping the download of optional components
[Common] Update config system

 - removed old listener based API
 - used NIO.2 for loading and saving
 - Fixed bugs
[easyQuest] Removed useless config listener reference
[MapEditor] Improved loading and saving of map files
[MapEditor] Properly report startup done
[Download] Fixed application started report for all applications
[Common] Improved configuration dialog
[easyNPC] Fixed multiple bugs

 - Fixed issue that all scripts got marked as changed after loading
 - Fixed issue that open script dialog started in wrong directory
[easyQuest] Fixed errors in configuration
[easyNPC] First working language definition for easyNPC in antlr4
[easyNPC] Entire parsing designed to work with antlr parsing

The documentation is now not properly working anymore and needs to be
written again.