py: loadable application support

python_payload/apps/__init__.py

python_payload/apps/demo_cap_touch/__init__.py

python_payload/apps/demo_cap_touch/flow3r.toml

python_payload/apps/demo_cap_touch/main.py

python_payload/apps/demo_harmonic/__init__.py

python_payload/apps/demo_harmonic/flow3r.toml

python_payload/apps/demo_melodic/__init__.py

python_payload/apps/demo_melodic/flow3r.toml

python_payload/apps/demo_scroll/__init__.py

python_payload/apps/demo_scroll/flow3r.toml

python_payload/apps/demo_worms/__init__.py

python_payload/apps/demo_worms/flow3r.toml

python_payload/apps/nick/__init__.py

python_payload/apps/nick/flow3r.toml

python_payload/main.py

python_payload/st3m/application.py