[Feature Request] Change filename characters with Dynamic Downloads/Rename and Route

[LukasThyWalls]

Hello.

I don't know if it can be done right now, at least i don't see how to do it, but the point is to change some characters for others of the renamed filename.

For example, i want to use part of the pagetitle (eliminating the last part), but also change the spaces to underscores in all the filename:

• pagetitle is "This is image 12345 on this webpage"
• I want the filename be "This_is_image_12345.jpg".
  I can do "This is an image.jpg", doing "pagetitle: (.+) on this webpage" and ":$2:.:fileext:" ($1 will be entire title) , but I don't see how to do it.

Also if I can do something like from pagetitle "This is image [12345] on this webpage" to "This_is_image_12345.jpg" (not only changing characters for others, also eliminating or changing some characters to nothing) it can be useful.