Some updates and Linux probably working better now

The most important update is for Linux users, as now I have tried a new way to turn it into an executable using Nuitka.  Linux users will need to use unzip or tar to extract the folder which contains the executable and supporting files.  This should hopefully now contain everything needed so it will not need to depend on libraries installed on your system.  It probably only works for Debian-based flavors.  Let me know if it doesn't work for you!

There were various cosmetic fixes, likely only noticed by me.  

Finally, I added a new tutorial level, which only has four bubbles.  I found that five bubbles is actually pretty tricky for beginners, and this four-bubble level is a great way to teach common patterns to look out for.  New players must reach 20 points in the tutorial level before level 5 "simple" unlocks.  Once the tutorial is passed, the only way to get back to it is to reach the end of the instructions, where the button appears to play it.  It's not meant to be a level that's regularly played.  

Also, I added locks to time trial.  Once tutorial is passed, both normal and time trial are available for level 5 "simple", but unlocking level 6 in normal mode does not unlock time trial for level 6.  To unlock time trial, you need to reach 20 points in level 5 time trial, and so on to unlock time trial for each level.  (It only takes five solutions in a row without using undo to reach 20 points.  One magical day I unlocked time trial on all levels by achieving 20 points on level 11, so it is possible.  I haven't been able to replicate that since, and reinstalling erased my progress, of course.)  I hope that this gives players another quest.