Add the abbiliy to exclude path

[bouda19]

Hi,

It could be great to add an option to exclude Typescript files.

Example : tplant --input src/**/.ts --output uml/uml.svg --associations --exclude src/extensions/.ts

My use case is that I have created extensions for some class in the src/extensions/* folder and plantuml does not support that. I would like to exclude all the files in this folder and keep all other files contains in src/**/*.ts to generate the uml.