Here are the updates for 0.12a.

Please have a look and see if something is amiss.
I have tested it on a custom STM32F746 board with 4-bit SDIO.
Sadly I do not have the boards that are used in the demos, so I just updated them with the new ffconf.h and fixed the main.c for the new features (corrected calculations and updated file-tree printing function).
What have been tested/done:
* Correct card size/free space
* Read
* Write
* FAT32
* exFAT
* Updated demos (ffconf.h / main.c), but only compilation test - no run test.