7.2 color definition issues

[mikekazakov]

7.3.1.1 states that rgba_color stores color information in premultiplied format, which contradicts existing implementation and how such objects usually work. Apparently this is wrong and usage of "straight alpha" should be specified instead.
The same issue applies to 7.3.3 and 7.3.4.

[mikekazakov]

Another interesting side effect of this issue is that, according to current specification, the following is true:

rgba_color c = {...};
float m = ...;
rgba_color d = c * m;
c *= m;
assert( d != c );

Maybe a separate issue but there is no color space specified. If we store both sRGB and Rec. 2020 colors in the same type we'll have Mars Orbiter situation again.