common: implemented improved EBML dumper class
translations: Polish installer: change encoding to Windows-1250
mmg: chapter editor: output exception's text in error message
libebml: update to a366eaa
mmg: only copy values for selected item on begin drag

Not of the item being dragged. That might not be selected, e.g. on
Windows.
ebml_dumper_c: enable all features by default
debugging: make debugging_option_c instances re-evaluate their result upon invalidation
debugging: debug options can be turned off internally again
logger_c: only append a newline if the message doesn't already end in one
debugging: move mxdebug() to debugging.h; option for redirecting debug output to logger
debugging: refactor functions into debugging_c; use debugging_option_c more
qtmp4_reader: remove debug message
debugging: refactor mxhexdump() into debugging_c
refactoring EBML_ID() checks to use Is<>(); more variations of Is<>()
refactoring: move ebml_dumper_c to debugging.h
wx debugging: ostream<< for wxTreeItemId
mmg debugging: write debug messages into the logger
mmg: add debug messages for chapter editor's D&D code
translations: update list of translatable strings
translations: update German