Run valgrind memcheck in CI

[nopeslide]

I found a few memory errors with valgrind in the base code.
To prevent such things in the future I propose running all tests with valgrind

[alrevuelta]

Yes, this is something that was definitely missing. Which specific memory errors you had?

[nopeslide]

Yes, this is something that was definitely missing. Which specific memory errors you had?

you duplicate a string when integrating the input into the model.
this string had a fixed allocation size of 50 and it seems some model or input had a longer name :D
I implemented some std string utilities (strnlen,strdup, strndup) to replace this allocation in #53.
see 6705c6f