Merge pull request #8 from MSeal/master

Rearranged file contents and removed some whitespacing
Make SheetYielder iterable for row production
Have SheetYielder provide sheet length
Merge pull request #9 from lorenabrams/import-export

Ensure SheetYielder iteration produces rows
Fix sheet yielder row generation slicing, add test for slicing functionality, and fix value equality testing to be able to test integer values
Pull version out to a veriable in setup.py
Merge pull request #10 from lorenabrams/fix_table_slice

Fix sheet yielder row generation slicing, add test for slicing functionality, and fix value equality testing to be able to test integer values