Put search_time in seconds in info

[johannes-fischer]

To make it even more consistent with JuliaPOMDP/POMCPOW.jl#32.

I just found it annoying when switching back and forth between MCTS and POMCPOW that one provides :search_time and the other :search_time_us in the info dict.

[zsunberg]

@johannes-fischer Thanks! I agree this is better. Waiting on the tests to pass. The question is, do we need to tag v0.5 after this since it is technically a breaking change?

[johannes-fischer]

Good point! It seems that in POMCPOW you have not tagged a new minor version after the equivalent change, only a patch. I think is shouldn't be a big issue to fix for users, since it doesn't really change how you use MCTS, only how the result is represented (still somewhat part of the API though).
Alternatively it's also possible to provide both in info until the next minor version increment. But then it's probably easy to forget to remove it later on.