Update colourspace example for more complete coverage

[barretpj]

Example now includes 3 plugins, to exercise Basic, Core and Full styles.

[revisionfx]

Thanks

Is there a difference between?:
ROLE(kOfxColourspaceRoleColorTiming, "Color Timing role (Arbitrary scene log)"),
ROLE(kOfxColourspaceRoleCompositingLog, "Compositing Log role (Arbitrary scene log)"),
Is there a difference between?:
ROLE(kOfxColourspaceRoleMattePaint, "Matte Paint role"),
ROLE(kOfxColourspaceRoleTexturePaint, "Texture Paint role (Typically sRGB)"),

[barretpj]

Is there a difference between?: ROLE(kOfxColourspaceRoleColorTiming, "Color Timing role (Arbitrary scene log)"), ROLE(kOfxColourspaceRoleCompositingLog, "Compositing Log role (Arbitrary scene log)"), Is there a difference between?: ROLE(kOfxColourspaceRoleMattePaint, "Matte Paint role"), ROLE(kOfxColourspaceRoleTexturePaint, "Texture Paint role (Typically sRGB)"),

Not relevant to this PR. These are the spaces/roles define in the OCIO config we use.

[Guido-assim]

These plugins are very nice to check the behavior of the host :-).
Maybe a hypothetical case, but if the plugin specifies a basic color space as an output color space then the host doesn't know what the exact color space is that is used. The host might need to convert the output of the plugin to another color space for display or other reasons.

[john-paulsmith]

Maybe a hypothetical case, but if the plugin specifies a basic color space as an output color space then the host doesn't know what the exact color space is that is used. The host might need to convert the output of the plugin to another color space for display or other reasons.

Not specifically relevant to this PR, but my recommendations would be:

1. Plug-ins should use cross-referencing for the output clip unless absolutely necessary.
2. When using the basic style, plug-ins should not perform colourspace transformations to anything other than ofx_raw (e.g. motion vectors).
3. If the plug-in does set a basic colourspace on the output clip, the host should interpret that in the same way it would if it was supplying images to the plug-in using that basic colourspace.