Replace pattern

[CodeF0x]

Right now, one can use {{name}}, {{ext}}, {{dir}}, and {{parent}} in the output pattern. An addional pattern for string replacements would be useful too.

For example, something that would allow to replace all occurrences of "h265" with "av1".

Added the "help wanted" label because input form other people how that pattern could look like syntax wise would be much appreciated.