Replace SpiderMonkey's Math functions with platform consistent versions

[historic_bruno]

As Philip reported on ​Bugzilla, there are differences in SpiderMonkey's floating point ​Math functions on different platforms. Even a small discrepancy can cause OOS errors in multiplayer games, if those functions are used in e.g. simulation, map generation, or AI code. We already use fixed point approximations for sin/cos and atan2 in the engine, but not yet for scripts. Currently no scripts appear to use atan, acos, or asin.

(There may also be differences in pow and exp which we do use rarely, but I wasn't able to reproduce them with the above test cases.)

[quantumstate]

The sin/cos approximations which are accurate to about 10^{-9 have been added with commit ​http://trac.wildfiregames.com/changeset/11226 . I will look at writing a good approximation for atan2.}

[historic_bruno]

Updated title and description since fixed point is no longer the focus.

Also [11220] is relevant, it introduced a new rmgen function GetAngle, which calls Math.acos. I don't know if acos is even a problem, I simply mentioned all the trig functions :)

[quantumstate]

In 11231:

Added atan and atan2. Refs #1193

[historic_bruno]

This ticket is probably solved well enough for Alpha 9. Would be nice to add some tests eventually.

[quantumstate]

These changes should fix the ticket, will wait till after A9 to commit them

[k776]

Bump. Can we get this finished up easily?

[leper]

A slightly modified version of the last diff was applied in [11363].

[quantumstate]

This is not closed because we were wanting to add some tests. I should get round to this sometime soon.

[historic_bruno]

I would suggest that as described in #433, the Math tests be run at game startup by everyone, not only in the standard test suite. That way we can hopefully detect problems like [11857] sooner and with more explicit errors.

[ben]

In 12056:

Implements global tech modification function. Fixes #1358, refs #1520.
Applies tech modifications to template data returned by GuiInterface?.
Extends engine to load arbitrary global scripts, separates this from RNG replacement. Refs #1193.
Loads global scripts for most script contexts for consistency.
Adds simulation tests for global scripts.

[historic_bruno]

Should also replace Math.pow and Math.exp at some point.