Syntax highlighting seems weird for many Elixir Kernel SpecialForms and Macros

[andykent]

Syntax highlighting for many in-built keywords seems to be a bit odd. I think at least some of this may be a regression since the recent 0.4.7 release but not 100% certain, I'm certainly noticing it more recently.

Below is a screenshot showing some of the weirdness. I note:

• def foo seems to highlight differently from def foo(). The def foo highlighting looks better and easier to scan but def foo() is more consistent with the other highlighting.
• do and `end seem to highlight correctly (purple in this case) but the other SpecialForms / Macros that would be considered keywords in many languages don't highlight differently to other function calls which leads to code often looking quite unbalanced.
• I'm not 100% sure what the correct behaviour is in all these cases but in daily use it doesn't feel like it's quite right currently.

[raulchedrese]

@andykent Thanks for taking the time to submit an issue. I agree this doesn't seem quite right. I don't think I'll have time to look at this soon but if you're interested in taking a crack at it I suspect we just need to tweak the tree-sitter queries here.