PEMDAS Widget, an advanced calculator for Dashboard

PEMDAS Widget is a simple yet powerful calculator for Dashboard in
OS X.

Not only does PEMDAS Widget let you work with equations, variables,
different bases, and many functions, but since it runs in Dashboard,
it's lightweight and is always just a key press away.
Merge pull request #2521 from vmrob/pemdas

PEMDAS Widget, an advanced calculator for Dashboard