This caused issues when saving the user module with commands defined
inside it, as it resulted in the user-defined commands trying to
overwrite themselves and failing.
When a command is performed with parameters, those are now passed to the
predicate.
The predicate can then return, after the validity boolean, any other
value that will then be passed to the actual command.
If the predicate only returns the validity boolean, the original
parameters are passed through to the actual command.
This allows predicates to manipulate the received parameters, and allows
them to pass the result of an expensive computation to the actual
command, which won't have to recalculate it.
String and table predicates will now also return `core.active_view`.
Useful to draw whitespaces with alternate characters and colors
without slowing down the text rendering.
A new API is implemented. A renderer.replacements object can be created
to list the replacements.
In turns the function renderer.draw_text and draw_text_subpixel now accept
two optional arguments for replacements.