Removing angle brackets from the language configuration

[racz16]

VS Code uses the brackets listed in the antlr.configuration.json file's brackets property to color the corresponding brackets with the same color. However, if it finds a closing bracket, without an opening one, it colors the bracket red. When we send a token to a channel, the angle bracket of -> becomes red. This is why I removed angle brackets from the language configuration.
Before:

After:

[mike-lischke]

This depends also on the theme. The main problem is that the arrow and other syntactic elements are not handled by most themes, which is why I added one which does. That looks then so:

but of course not everyone likes this.

To be able to merge I need the DCO check to pass. Please check that (follow the Details link)

[racz16]

Yes, I think your theme is good, but people need to switch to it manually or they just don't want to use it. I fixed the commit.

[mike-lischke]

Please sign your commit if you want it to be merged.

[mike-lischke]

@racz16 Last chance to sign your PR.

[mike-lischke]

Thanks!