Read `file://` as absolute in `resources.lua`.
Read `file://` as absolute in `resources.lua`.

I made a mistake in recognizing `file://` as a relative & local file. It
*is* a local file, but it is also absolute, so we should ignore it
regardless.

This commit also simplifies `resources.lua` a bit.

slakkenhuis/snel,slakkenhuis/snel