Packages have been split into:
- easytracker-base, providing `easytracker/` package for the
  base interface
- easytracker-python, providing `easytracker_python` package
for the Python tracker
- easytracker-gdb, providing `easytracker_gdb` package for the
GDB tracker

Installation from source can now be done through `pip -e ...`
foreach package dir as described in the `README.md`.

Legacy source based execution is preserved when `PYTHONPATH=$PWD`
though this may be removed in a future version.

In order to use the visualprimitives module which is not
packaged, one still has to setup `PYTHONPATH=$PWD/extra-packages`
and install requirements with
`pip install -r extra-packages/requirements.txt`.

In order to build and publish new Python packages on GitLab,
the following make targets were added:
- make dist: create dist packages
- make dist-upload: upload dist packages to GitLab
- make dist-install: install locally dist packages

Compilation of libraries for the GDB tracker is no longer
necessary and is done on the fly when initializing the GDB
tracker.