Feature Request: Syntax Extensions via Hooks

To my knowledge, Task Warrior does not really have a good way to support syntax extensions at the moment. For example, if I currently put a task as `due:monday` it will make the task as being due the date of the next monday, at 00:00:00. However, one might want to instead have a shorthand for monday at 23:59:59. To resolve this issue, it would be nice to be able to write `due:monday-eod` or something to that effect. This is currently not possible with Hooks as parsing happens before hooks execute, and `monday-eod` will fail to parse correctly.

One way to address this, and perhaps the easiest way, would be to allow for hooks before parsing. This way, the syntax extensions could be accomplished by simply find and replacing one's desired syntax with an elaboration. I currently do this via shell scripts, but I would rather have a hook for it.