Improve Support for String Messages
The string type defined in types.room simply maps to char pointer and if users aren't aware of this, they can quickly end up with invalid pointers.
We decided to introduce an annotation for messages of type 'charPtr', e.g. '@StringMessage'. The annotation signals the C generator to create code that copies the string into the message payload.
The old string type in types.room should be marked as deprecated with a hint to the new message annotation.