Istraia STG Demo ver. 0.3 update

I updated the demo of Istraia STG to 0.3, with it`s version downloadable, and here are some few changes and fixes to the demo:

-Fixed some ground-type enemies where touching them directly would kill you.

-Some stuff were slightly tweaked.

This goes to show some improvements that are being done to Istraia STG, showing the many trial and errors I will have to go trough on creating shmup games.