[BUG] Zero-pitch change ignored

[YaroslavKormushyn]

I have found that when setting the pitch dynamic property to [0] the change does not propagate to the map instance. This is because when checking the values of the move method options we ignore all 'falsy' values instead of checking for an actual value.

ngx-mapbox-gl/projects/ngx-mapbox-gl/src/lib/map/map.service.ts

Lines 255 to 263 in e5af644

	return this.zone.runOutsideAngular(() => {
	(<any>this.mapInstance[movingMethod])({
	...movingOptions,
	zoom: zoom ? zoom : this.mapInstance.getZoom(),
	center: center ? center : this.mapInstance.getCenter(),
	bearing: bearing ? bearing : this.mapInstance.getBearing(),
	pitch: pitch ? pitch : this.mapInstance.getPitch(),
	});
	});

This check for zoom or center makes perfect sense, but for bearing and pitch zero values should be taken into account.
What do you think?

[dmytro-gokun]

@YaroslavKormushyn You are probably right and we should use '!= null' comparison for all four parameters. Please go ahead and put up a PR

[YaroslavKormushyn]

Fixed in #335