The full list of changes is included in the
versions.txt file that comes with each release. In the case of ini file handling, this issue is related to number 2 in the change list:
2. mIRC now uses its own custom ini routines to ensure more reliable ini file handling. They should work almost identically to the standard Windows ini routines.
The issue with quotes for ini file section/item/data has been fixed for the next version.