ignore 'hidden' files when creating a project

[Abe404]

I had created a project using the hepatic vessels data from http://medicaldecathlon.com/

The dataset had files in it such as ._hepaticvessel_333.nii.gz

As far as I know, these are metadata files for OSX. I think it is safe to assume if a file starts with . then it should not be read by RootPainter3D.

Alter the create project functionality to ignore such files as I do not want them to end up in the created project file.

[Abe404]

Based on discussion with @rohanorton we are using this issue as an opportunity to setup some automated tests. Then will likely address this issue using TDD.

We also discussed client python version and decided it makes sense to test with python 3.11, as it's arguably the best (new performance improvements and features etc). The version of python of the end user is not something we need to consider as this is for the client and we bundle the python interpreter with the client so we can control the version.

We also agreed, arbitrarily (and for now), to have the tests co-located with the source code.