v0.4.0

fix readme again

v0.3.0

fix the mess with versions

Use dirname instead of split

os.path.dirname() is identical to os.path.split()[0] see: https://docs.python.org/3/library/os.path.html#os.path.dirname

Support for new pythons (#9)

* bump version

* add 3.7 and 3.8 to travis

* remove support for 3.3

* add test for checking if letter is a string