Remove limits for importing test cases

[magsilva]

A long time ago, I faced a issue when importing test cases. For instance, I tried to exhaustively create and add test cases to current project (test set):

for month in `seq 1 12`; do
  for year in `seq 1 9999`; do
     tcase -add -D /media/disk/Cal -E cal  -p "$month $year"  -EE
__cal_inst -trace cal;
  done;
done

However, only 512 test cases could be imported. It would be important to remove such limit.

Currently, to keep working with more than 512 mutants, we can workaround this by importing as much as 512 test cases, run the mutants, and run tcase with the option to remove test cases that could not kill mutants. This should free some space to import new test cases.