Autocompletion for TEdits fixed for Delphi 11 and later

[dummzeuch 1467]

My dzlib contains several helper functions to add TEdit-autocompletion for directories, files (with a filter) and generic strings from a string list. All of them worked fine for me and were used in several our internal programs. But that changed when trying them with Delphi 11 as @Carlo Barazzetta found out: Using these functions now raised a system exception as soon as the IEnumString.Next method was being called the first time. It turned out that the way I tried to cheat with the memory allocation of WideStrings no longer works. Read on in the blog post.