send_fake now copies almost all field from the original event, except for the the window, keycode and state field. When we grab a key we grab it onto the root window, so every event we receive has a field window that is equal to the root. (this will change in the future), so we need to change that. The keycode and state obviously need to be changed, it's the whole point of the function. It doesn't seem to fix the known bug that occur in dino thought.

users can now exec command on specifics keys. For example: match class Something on "C-<F5>" do exec my-program

yyerror now is a printf-like variadic function. This helps to generate custom error message like "invalid keysym %s" or "invalid key %s" during parsing.

Rationale: sometimes it can be useful to globally bind a key. For instance, some users may like to bind on "C-<Up>" do "<Page_Up>" for every application.

the default error handler violates the pledge "stdio" by trying to read (and possibly also write after) some files. Also, I don't like my program to be randomly killed if I try to get class hints on a window that doesn't have any.