[5.1] Remove template special color

[wilsonge]

Summary of Changes

Removes the template special color from core. The only potential place this is used is in toolbar secondary buttons. As far as I can tell no core extensions actually use this. But there is a chance third parties do. We now revert back to using the default bootstrap secondary color in this case.

This is a b/c break if other people are using this CSS Var. However I can't see any obvious way for us to actually deprecate CSS variables.

Testing Instructions

Change the class of an existing button from btn-*** (success/error/action) etc. to btn-secondary.

Link to documentations

Please select:

• [ ] Documentation link for docs.joomla.org:

• [x] No documentation changes for docs.joomla.org needed

• [ ] Pull Request link for manual.joomla.org:

• [x] No documentation changes for manual.joomla.org needed

[Cybernary]

Have tested this successfully.

[HLeithner]

@wilsonge deprecation is at least needed in the manual. is it critical to remove it in 5.0 or 5.x?

[webmasterab]

Tested this but it seems that this has already been resolved.

For patch test installed after patch test Removed again after patch

[HLeithner]

This pull request has been automatically rebased to 5.2-dev.

[Hackwar]

@wilsonge could you update the PR to solve the conflicts?

[Hackwar]

@wilsonge Any news about this one?

[rdeutz]

I have solved ther conflicts this needs to be tested

[Bodge-IT]

Tested, btn-secondary resolved to same colour before and after patch. Special color gone from Atum options.

No 'result selection' options in https://issues.joomla.org/tracker/joomla-cms/42017

[Bodge-IT]

@wilsonge Can you please have a look at this and see if it's still relevant