Add fallback, receive, error as types of function declarations

[haltman-at]

Just noticed that I'd totally missed updating this. Obviously fallback, receive, and error all got added to the list of keywords, but not here. So I've added them here now. (Obviously error isn't actually a type of function declaration, but it makes sense to highlight it the same way, and event is already included here for the same reason.)

[frangio]

To be honest I'm not sure what is the exact effect of this change so I trust you on it.

[joshgoebel]

Of course function CSS class will be deprecated in v11... we're getting away from block scopes in favor of tighter scopes like the new title.function for JUST the function title. The guide I wrote for theme makers has some guideance:

highlightjs/highlight.js#3134

[haltman-at]

To be honest I'm not sure what is the exact effect of this change so I trust you on it.

The idea is that the same title stuff that the same title/parameter highlighting we apply to function and event declarations will now also apply to error declarations and fallback declarations. For receive I don't think this does anything since those have no parameters, but fallback has allowed a parameter & return value since Solidity 0.7.6.

[haltman-at]

Of course function CSS class will be deprecated in v11... we're getting away from block scopes in favor of tighter scopes like the new title.function for JUST the function title. The guide I wrote for theme makers has some guideance:

highlightjs/highlight.js#3134

Oh, huh! OK, that will have to be handled later as part of the transition stuff, I guess. Thanks for pointing this out!