post beta2 fixes

midb.asm:
exception handler for peripheral 68881 writes into location 0
This is now fixed

midb.asm:
fcmp2fp was defined as $5428, it should be $5438, this has no
material affect since we use a software comparison algorithm anyway.

Changed spc5.asm to not do overflow trap on indefinate result.
Now NAN is returned without tripping exception.

Changed cxt5.asm to use asl.l #1 instead of cmp.l $80000000 
This is 2 word smaller and about 1usec quicker.

Removed many unused files.
Renamed most of cx? files to more informative names like fdiv.asm

Made the init routine call exec_patch if 68020/68881 and exec version
is less than 35. This library is no longer expungable.

Now using and asl.l #1,d0 in fcmp.
Also tidied of Close/Expunge for when it is made expungable later on.

fabs and fneg now coded into the library vector table itself. This will
double the speed of those routines.

Removed code to do 68020/68881 patch up. So this library
is now expungable again. That code moved to setalert as a patch
program to be run on 1.3 release wb.

May 27, 1988
   Rethought out the exception strategy. This is going to be punted
for V1.3 and will be reinstalled in V1.4. This will mean the library
no longer will generate exceptions on overflow or divide by zero.
See float.i to have it reinstalled. The code that controls the 68881
stuff checks for ALLOW_TRAPS being defined also.
Dale

May 27, 1988
Expunge now protected by Forbid/Permit. Needed because Close would 
jump into it and Expunge dicks with unprotected data structures.

May 29, 1988
Changed software overflow return value to return largest (+/-) instead of INF
according to 68881 rules regarding rounding to zero.

June 13,1988
May 27,1988 introduced bugs. Permit can destroy d0, so moved the loading
of d0 to after the Permit call.
Also the Ext functions were improperly returning seglist when they should
have been returning d0=#0

 
August 24,1989
mixed midb.asm to work with 68882, the NULCA macro was not
properly decoding the primitive responses
Broke the macro out into it's own include file 'nulca.i' so
that the midb.asm in the other libraries can refer to it.

