Moved opening animation

Finally, the entire opening monkey animation appears after each game start, not only after loading the game, on all Spectrum compatible computers including Spectrum 48K (except Spectrum 16K, of course). Therefore is was removed from the introduction after loading the game. It still needs some tweaking to make it look exactly like the previous version of the animation, but it is already a pretty decent achievement.

One side effect of this change is that the monkey in the opening animation is more stable at the bottom of the screen and shouldn't flicker there on any supported computer, even on Timex and Dubna.

A small colour error on a barrel jumped over by Mario is fixed.

Now that the memory in the screen buffer has been freed up (previously used for the animation), I can add more things there that will be available after loading the game (or before each game start on Spectrum 128K and Didaktik Gama).