Replacing magic constants with std::numeric_limits in id suggestion handling

The old code made use of magic constants like 0x00ffffff to signify
arbitrary long strings or arbitrary many words/authors/...
At one point, -1 got assigned to an unsigned int to set it to its
maximum value.

The new code makes proper use of std::numeric_limits<int>::max() to
signify 'arbitrary many' words/authors/characters for a id suggestion
template.