Ontoloviz

- fixed bug in save function caused by `is_a` attribute in custom .obo ontologies

- added option to automatically convert floating point numbers to normalized integers when loading custom ontologies

- Added option to show icicle plot & treemap for separator-based ontologies
- Fixed a bug in parent-based ontologies where non-unique occurrences of children were excluded from the plot

- added support for separator-based ontologies
- added support for parent-based ontologies
- added fetching of .obo ontologies from the web
- added color-bar as legend
- added color-pickers
- various bug fixes, refactoring, improved documentation

- reduced filesize of Windows executable
- percentages of counts displayed as tooltip are now affected by the color: global setting
- drop empty nodes now removes empty phenotype subtrees entirely
- major redesign, current mode (phenotype/drug) is now displayed in title
- pylint cleanup
- renamed ToolTip variables, added docstrings
- renamed test.py to app_test.py to fix automatic collection with pytest, added dependencies to python-package.yml
- switched to poetry as build backend, bumped to v1.5.0
- added prompt to generate new template after ploting, prevent window resize, code cleanup & limit to max. 100 characters per line