Passing something non-constant at compile time here is extremely dangerous, especially when users can replace those strings if they like.
It now uses FString::Substitute in all cases where something needs to be inserted into a template string.
This deals with what seems to be the only hardcoded piece of text in Strife. Also added a translation to the French file and removed a few superfluous line breaks in the English one.
Note that this completely disables the newly added keywords 'play' and 'ui' for unversioned code to allow using them as identifiers as I have found at least one mod that uses a variable named 'play' that would have been rendered broken otherwise.
This also disables many ZScript only keywords for other parsing jobs.
- do not resolve the backdrop texture to a texture ID at load time. This will allow custom menu classes to use this info differently.
- added a new ZSDF userstring property to dialog pages to give mods more means for customization.
- allow overriding the conversation menu class both globally through MAPINFO and per conversation in ZSDF.
