Float numbers precision in arithmetics

[romaintailhurat]

We witness some weird behaviors when doing scalar operations involving float numbers. Here are two examples than can be reproduced in the Trevas storybook:

• with {"a" : -4, "b": 50.21} as bindings, a + b gives 46.21
• with {"a" : -48, "b": 50.21}, a + b gives 2.210000000000001

Using round(a + b, 2) is a temporary bypass but we should be able to fix this issue directly in the engine.

[romaintailhurat]

@NicoLaval so no other solution than manually round, the results are on par with what every language does.