v2: Add experiments->events converter (PEtab-dev#387)

Add functionality to convert PEtab v2 experiments/conditions to SBML events. This should make it easier to implement v2 support in other tools. 

All condition table changes are converted to event assignments. Only two indicator variables have to be set for each experiment.

Closes PEtab-dev#370.

---------

Co-authored-by: Dilan Pathirana <59329744+dilpath@users.noreply.github.com>

Author: dweindl

doc/modules.rst

@@ -32,6 +32,7 @@ API Reference
    petab.v1.yaml
    petab.v2
    petab.v2.C
+   petab.v2.converters
    petab.v2.core
    petab.v2.experiments
    petab.v2.lint

petab/v2/__init__.py

@@ -37,6 +37,7 @@
     models,  # noqa: F401, E402
 )
 from .conditions import *  # noqa: F403, F401, E402
+from .core import *  # noqa: F401, E402
 from .experiments import (  # noqa: F401, E402
     get_experiment_df,
     write_experiment_df,