[libfat] Fix a bug in _FAT_directory_mbstoucs2. Should access the data of the pointer, not the pointer itself.
Fix whitespace trimming in xstring.cpp. This function tries to check the leftmost char and see if it's a whitespace character. This if statement test is supposed to check if the char at position zero is not whitespace. However logical AND needs to be used over OR in this case, otherwise the check can succeed in invalid cases.
Fix if statement guards in slot2_Change and slot2_setDeviceByType.

Guards against the case some dinglenut actually passes NDS_SLOT2_COUNT as a parameter (really dumb in and of itself).
Do the same thing as the previous commit, but for slot1.cpp's slot1_Change()