clean.sh: fixed name of .tex files to be removed.
.gitignore: changed name of .tex files to be ignored.
test_span.pl: added parameter to create test permutations with
	      meaningful names (year, which test, which type). Added
	      parameter to call get_hdr (intended to be the name of
	      masterfile).
.gitignore, clean.sh, clones.sh, grade.pl, loa.pl: changed to fit the better names for the generated files, now indicating year, test and class.

mat2457-p{1,2}-t1.dat: renamed to include the year of the test.