Use ilu with type=ilutp instead of nofill

Contrary to luinc command ilu with nofill option doesn't not allow for partial
pivoting
Remove spurious displayed variables
Fix nonexistent variable names
Fix incorrect reporting of failed test number
Fix mangling of lasterror() under Octave
Disable test with block and stack_solve_algo=3 under Octave (Ref #407)
Introduced new options that allows to set prior (sign) restrictions to irf's