Change the return type of Stream_Ensure*Capacity from void to BOOL to be
able to detect realloc problems easily. Otherwise the only way to detect
this was to check if the capacity after the call was >= the required
size.
In case Stream_Ensure*Capacity fails the old memory is still available
and need to freed outside.
This commit also adds checks to most calls of Stream_Ensure*Capacity to
check if the call was successful.
