Get rid of the horrible eval
Remove the RAM requirements estimate

It's a very complicated piece of code that yields an extremely
inaccurate estimate of the RAM requirements. For example, a simple
IGO is estimated at around 9MB, but calling build() creates around
60MB. For things like HOGs it makes it seem as if you have enough
memory when you probably don't!
Merge pull request #377 from patricksnape/simple_fixes

Simple fixes
Update README.md