Removed Cell, map handles only cell types and checking validity.
Merge branch 'master' of https://github.com/Soaa-/towerdefense
Revert "Merge pull request #1 from Soaa-/Lori"

This reverts commit e3986ce9e9be0fdcdfe3b2bcb386329e1887a1b6, reversing
changes made to dd89942a3b5032d111581d779946d91b6015167b.