tdb_cons shouldn't append .tdb extension automatically

[oavdeev]

Makes things really unwieldly, for example if you create a traildb with a random name, you have to know that actual traildb filename is "random_name + .tdb". It also goes against what most APIs and CLI tools are doing.

Basically, this currently doesn't work and it is pretty inconvenient:

tdb make -o $RANDOMNAME
cp $RANDOMNAME $dst

Same logic goes for API.