This commit deals with the problem that the keyframe timestamps are not standardized. Seconds, milliseconds and ticks are used depending on the import format. There is no metadata or property that specifies the format used, so the option is exposed to the user as part of the import options gui.
This makes some tweaks to the engine to support this, specifically, it tweaks the hardcoded shaderpaths to defer to a pref variable, so none of the shader paths are hardcoded.
Also tweaks how post effects read in texture files, removing a bizzare filepath interpretation choice, where if the file path didn't start with "/" it forcefully appended the script's file path. This made it impossible to have images not in the same dir as the script file defining the post effect.
This was changed and the existing template's post effects tweaked for now to just add "./" to those few paths impacted, as well as the perf vars to support the non-hardcoded shader paths in the engine.
