[Ifeffit] odd feff6 behavior

[Matt Newville]

Hi Anatoly, Bruce, Carlo,

Anatoly is right on the meaning of the "np > np1x" message. It
would be trivial to increase this.  There are 4 integer arrays
and 1 double precision arrays with this dimension.  Increasing
this to 40000 would add less than a megabyte of memory. Anyone
remember when adding a megabyte here or there was a legitimate
concern?  It would probably let you go beyond 7 Ang in nearly
any structure.  Since feff6l is intended for EXAFS analysis (and
only EXAFS analysis), that seems perfectly reasonable to me.

But: I think the real problem ist that feff6l stops completely
with a cryptic Fatal Error message when it exceeds np1x paths
(even Bruce couldn't decipher it!?!).  Of course, it may have to
stop enumerating paths at some point, but it should continue on
to GENFMT if runs out of memory for the paths.

I'll try to make both changes for the next release, and look for
other silly 'Fatal Error' messages that could be warnings.

--Matt