Give plugin authors the chance to extend a palette

[BurningTreeC]

This PR changes the colour macro so, that it transcludes a tiddler with the name of the current palette but with the suffix /extension on the second position

This gives plugin authors the chance to extend palettes

[BurningTreeC]

bad idea @Jermolene ?

[Jermolene]

Hi @BurningTreeC I think this approach only allows one plugin to provide extensions for any particular palette. We should always be trying to minimise the chance of conflicts between plugins.

An approach that allows plugins to provide entries for particular palettes without conflicting with one another might be to support config tiddlers of the form $:/config/DefaultColourPaletteMappings/<palette>/<name>:

<$transclude tiddler={{$:/palette}} index="$name$">
<$transclude tiddler="$:/palettes/Vanilla" index="$name$">
<$transclude tiddler={{{ [[$:/config/DefaultColourPaletteMappings/]addsuffix<__palette__>addsuffix[/]addsuffix<__name__>] }}}/>
<$transclude tiddler="$:/config/DefaultColourMappings/$name$"/>
</$transclude>
</$transclude>
</$transclude>

The only conflicts with that design is if two plugins try to set the same entry for the same palette, but that's an intrinsic conflict that we can't resolve.

[BurningTreeC]

Hi @Jermolene , I've changed it as you said
I'll add some docs

[Jermolene]

Thanks @BurningTreeC I meant to add that we should also take this opportunity to replace the text substitution usage of this macro, please.

[BurningTreeC]

Thanks @Jermolene , I've updated everything accordingly

[Jermolene]

Thanks @BurningTreeC just a minor point.

[Jermolene]

Thanks @BurningTreeC

[Jermolene]

@BurningTreeC I have reverted this commit because it completely breaks colour handling:

Did you test it before submission?

[BurningTreeC]

Apologies @Jermolene - I tested it but there's one small typo