Add hashbang
Add separate reader and writer parameters

In case those are not provided, it will execute only transform. This
makes it possible to use the basic functionality without having to read
file contents always.
Update dependencies
Add .gitignore
Add .gitignore
Simplify import
Move toupper demo to its own directory
Allow input to be filtered using an expression

Use -E to pass an expression. -v can be used to optionally invert it.
0.3.0