Support for WKT CRS (global encoding bit 4) not avaialble for point types 0-5

[georgeboot]

I believe support for WKT CRSes is missing. This is enabled for all new point types (6-10) and optional for the other point types (0-5).

In the current implementation, this bit is set only for the point types 6-10, but it should also be available for point types 0-5.

las-rs/src/header/mod.rs

Lines 537 to 539 in bea51e5

	if self.point_format.is_extended {
	bits |= 16;
	}

[gadomski]

Good catch, thanks! Fix in #67.