Improve package structure

[mano8]

Changes:

• Improve package structure
• Improve code style
• Improve unit test coverage
• correct some bugs

[mano8]

ok

[codecov]

Codecov Report

Attention: Patch coverage is 92.74611% with 14 lines in your changes missing coverage. Please review.

Files	Coverage Δ
setup.py	0.00% <ø> (ø)
test/schema_test_helper.py	94.04% <100.00%> (ø)
test/test_config_loader.py	100.00% <100.00%> (ø)
test/test_config_loader_helper.py	100.00% <100.00%> (ø)
test/test_loader.py	100.00% <100.00%> (ø)
test/test_schema_app_blocks.py	100.00% <100.00%> (ø)
test/test_schema_app_connectors.py	92.18% <100.00%> (ø)
test/test_schema_battery_bank.py	98.71% <100.00%> (ø)
test/test_schema_data_structure.py	100.00% <100.00%> (ø)
test/test_schema_emoncms.py	92.85% <100.00%> (ø)
... and 36 more