txldefs.h: update some comments
swload.c: reinstate the truncation code from swtrunc.c
(was removed in a patch from 2001 04 25)
code for SENSDEBUG fixed
Makefile for SENSDEBUG fixed
bug fix, preserve filename case for `codemodel', `load' and `use'

reported and fixed by Emil Lambrache
in bug tracker
  "case sensitivity not preserved for file names - ID: 3611642"
  https://sourceforge.net/tracker/?func=detail&atid=423915&aid=3611642&group_id=38962
fix a wrong GMIN implementation
adapt the sense2 code to ngspice
fix an incorrect typedef and cast

which was of no consequence,
  because nobody made use of it.

ancient, already in the very first commit of ngspice
  Date:   Thu Apr 27 20:03:57 2000 +0000
workaround, make the opaque struct MatrixElement partially visible

this struct is private to the `sparse' world,
  and lives in "maths/sparse/spdefs.h"
which can't be included here, because
  it is incompatible to the rest of ngspice.

this is the same problem as in
  ciderlib/oned/oneprint.c
  ciderlib/twod/twoprint.c
cleanings for sens2 code wrt SENSDEBUG printout