#197 fix string size handling in Unicode builds

[Giermann]

Editing Notes is not possible anymore. Maybe it started with some Windows Update (Win7SP1 x64), but I traced it down to blame it on GetDlgItemText() in CEditDlgNoteText::OnChange().
It seemed to have some problems with too large requests...

Reading the code I found, that using sizeof() is unsuitable in Unicode builds without dividing through sizeof(TChar). I changed all occurences I found to the equivalent call with a CString instead of using temporaray fixed size buffers. Sometimes this was not suitable, where I fixed the use of sizeof() instead.

[Don Lucas]

The attached patch has been successfully applied to version 2.90.00. This version will be released soon. Many thanks to user Giermann, and sorry for the delay.