Performance fixes and zebra.c split
Created originally on Bitbucket by ppluciennik
Was already merged in Bitbucket before import, marked as merged by the import user
Some parts of code related to drawing were not optimal. I've decided to optimize them. After that I saw that there are two files that look similar (zebra.c and zebra-5dc.c). My idea was to split zebra.c and give ability to reuse code in zebra-5dc.c.
PS: I'm eager to help you in developing/refactoring code.