Added Open Recent functionality to File menubar item
Added new editor setting for Startup Mode to dictate if it'll open the most recent level edited or the blank level, instead of utilizing a game UI control for level selection.
Properly re-enabled the handling for the forceSidebarToSide setting to track to the setting value
This also fixes some insecure behavior relying on %this value eval'ing, which has also been modified to be better.
Also fixes up some old calls for getting menubar menus by internal name, which is no longer supported, instead using the findMenu function call.
Added a check so if no levels are found from other modules, the default ui module will prompt the user to launch the editor to the base editor level and begin editing or return to main menu if tools are present, or inform them to double-check that there are modules with gameplay/levels and return them to the main menu in no tools available.
Also set it up so if the editor is launched while a mission isn't running, it'll automatically load to the base editor level and set up a default camera object. This way editing can be done even if no level is currently loaded.
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.
