Bug squishing

I squished lots of small bugs in the past days:

• Current HP and MP are now saved to database, so players don't regenerate fully when logging out and in again
• Route finding isn't even attempted when destination is non-walkable. So when a character gets stuck in a blocked area, it can't walk around while staying in the same map participation rectangle (it would be better when they couldn't get stuck there in the first place, but that's another topic)
• Floor item stacks now have a quantity
• Name labels don't get detached from their objects anymore (I am drawing them on the canvas again - but now I am using caching to increase text drawing performance)
• Improved rendering performance by using insertion sort for sorting beings by draw order instead of whatever is the default sorting algorithm of the browser (the beings are only slightly out of order most of the time - in that special case insertion sort greatly outperforms all other standard sorting algorithms).
• Fixed the problem with newly created characters not showing up until the next login.
• Generated spell names: removed double space after level.

I also started a spreadsheet to keep track of known bugs I haven't fixed yet.