isometric + unittest

[JaskRendix]

PR splits out the isometric part from #62 and adds unittest to check the two methods.

[bitcraft]

thanks for the update. ill probably mention this again, but its been my experience than using the [] and {} syntax compared to list(), dict(), etc doesn't produce a meaningful improvement in performance. micro benchmarks aside, its not going to make rendering any faster. im not going to ask you to change it, but if i do, understand that i think in many cases, its a style preference i have that makes the code more readable.