Go to source code of packages and open manual of packages

[ghost]

I wrote a few methods which will help implementing the 'Go to Source Code' action.
For example in \usepackage{tikz} when one navigates to tikz and presses CTRL+B the source file should be opened.
To get this behaviour working I wrote one method for \usepackage*{packageName} one for \documentclass*{className} and one for included filenames using \include or \input or similar.
For each of these functions it is additionally needed to first look in the same folder as the tex file if the file exists there.

I also implemented a function which opens the manual file for packageName maybe this could be implemented too.

[stenwessel]

Looks great! We will try to get this working with the IntelliJ SDK