Is there a reason user defined gates are not supported?

[wjyoumans]

User defined gates are included even in the common include file qelib1.inc, for example:

gate sx a { sdg a; h a; sdg a; }

Is there any plan to support these? Is there a difficulty with adding them? (If it just hasn't been looked at yet I'd be happy to try myself, just making sure it isn't a well-known difficulty).

Currently these error with MissingSemicolon.

[wjyoumans]

I see user defined gates are supported, like the Hadamard gate in the README example. I think it is an issue with having multiple instructions in the definition.