Kernel-Tests: fix compilation error with new compiler

nonBoolean was an unknown variable before
UnknownVariableError: add >>messageText
Error: set default messageText to the name of the error class
ClassCategoryReader: remove unused variable 'chunkParser'
ClassCommentReader: remove unused variable 'chunkParser'
REPL.st: fix deprecation warning

use Class>>subclass:instanceVariableNames:package:
instead of Class>>subclass:instanceVariableNames:category:
REPL: recompile
ClassCommentReader: update class comment
Merge pull request #331 from mkroehnert/fixes

Compilation error/deprecations fixes + unused code removal