v1.2.3

#25 I added progress dialogs for loading and saving the project, so it should not feel that unresponsive. No final solution, but maybe it helps.
#30 For projects with many categories, the selection of a category when adding a replaement can be annoying. The new searchable control fixes the problem.
#31 The project could be corrupted when marking large sections (>32000 characters). This is not possible anymore.
#32 The built-in backup is fixed for windows machines. But please: BACKUP YOUR PROJECT REGULARLY!
#33 Display alert windows, when there is an error in the log