Make high-level keycards open lower-level doors

[hikagura99]

Feature Summary:

I think everyone agrees, the developers too, that switching between 8 cards just to find the right one is not a difficulty enhancer, but just a poorly thought mechanic (hence the "shortcut" keycards in MG2, or the simple upgrading of them in MGS1 and 2). So basically what I'm asking, if possible, is to add the effect of all the previous cards to higher ones in Metal Gear 1.

[ShizCalev]

Should be possible, I have been poking around a bit at MG1.dll (which is the full MG1 game), so i'll see what i can get goin