Resource conservation

[wchill]

• [ ] Only keep the last 20 or so Pokemon on the map (maybe make this user selectable)
• [ ] Only keep track of the last 10000 or so steps on the map (maybe also make this user selectable)

Should keep RAM usage lower and also make the UI a bit smoother after it's been running for a while.

[niicojs]

I added a proto in my dev branch (http://openui.nicontoso.eu, github: https://github.com/nicoschmitt/openui).

Basically it defined max (50 pokemon, 10000 steps). When it attain the limit, it keeps only 70% of limit and redraw map.

50 seems kind of low to me at the moment. Browser can handle a lot more, the question is: what UI will look like with 500 pokemon displayed. Normally I would say it's fine, but as the bot has a tendancy to walk in circle for the moment all pokemonq are caught in the same area. So I'm keeping 50 (which bounce to 35 is reached)