user dictionaries at ~/.local/presage; small cleanup

[rinigus]

I have

• modified destructor of PresagePredictor (lost the timer loop and deleted non-nullptr; please let me know if timer loop was needed)

• made user database path in accordance with common directory paths of current envs (.local/presage/...)

• added parent to the engine in its constructor to avoid it dangling around

So, its mainly about memory management and I hope its not breaking anything. As far as I can see, it worked fine.

[martonmiklos]

The die timer is a kind of residual non-working code piece as the result to create workaround for the situation described in #1.

I am fine with your changes, thanks for the improvements!