I'm getting segfaults in yb_any_file_rclose (closing a file opened with
yb_any_file_ropen with type MIDAS).

I think there are bugs with freeing from uninitialized pointers my.pmagta,
my.pyh, and my.pylrl (which are only set when opening a YBOS file).  These
should be set to NULL in yb_any_file_ropen (case MIDAS).  Likewise, the MIDAS
format pointers my.pmp and my.pmrd should be NULLed for YBOS opens. 

It might be wise to also initialize the pointers in the "my" structure to null.

--Donald