Fix bug: wrong filename generation

Bug description:
 ./script/runtime -p C c1 c2 -p B b1 b2 -p A a1 a2 -u 'Clx(AcxBf)' -- '/bin/echo "A B C"'
doesn't create all the files

Issue:
-> generation of file names are wrong: time_C.c1_B_A
In fact, B should be valued and C should not.
Remove useless function ast_get_dimension_index
Bug fix now handle multiple occurrences of the same parameter name in the using expression correctly.
Add canonical representation of tuples in result dbs.
Remove now redeundant parameter name field in value space
Fix automatic assignment of format specification
Add TODO file