lualoader: More black-on-white fixes

To recap the problem: with a black-on-white xterm, the menu draws terribly.
Ideally, we would try our best for a white-on-black context for the menu
since graphics and whatnot might not be tested for other setups and there's
no reasonable way to sample the terminal at this point for the used color
scheme.

This commit attempts to address that further in two ways:

• Instead of issuing CSI bg/fg resets (CSI 39m and CSI 49m respectively for "default"), issue CSI bg/fg escape sequences for our expected color scheme
• Reset to *our* default color scheme before we even attempt to load the local module, so that we personally don't have any earlier text with the console default color scheme.

Reported by: emaste (again)