Implement simple LCT model

[lenaploetzke]

Feature description

• add lct model
• simple example
• related tests
• replace print by print_table

Additional context

Copy code from #680
Files:

• lct_secir without initialization, parameters_io
• example lct_secir
• test

Checklist

• Attached labels, especially loc:: or model:: labels.
• Linked to project.