* adds related eco account withdraw detail view to intervention detail view
* adds new route for removing withdraws using RemoveModalForm
* adds EcoAccountWithdraw model
* adds admin interfaces for EcoAccount and EcoAccountWithdraw
* adds message_templates.py to konova/utils for reusable messages
* splits related-documents.html and related-objects.html into separate templates for each related object type: compensations.html, documents.html, eco-account-withdraws.html and payments.html
* adds translations
* adds help texts to add payment form
* adds removing button for payments
* refactors user fetching into BaseForm
* adds generic RemoveModalForm which is intended to be used for every modal form which shall remove something
* adds translations
* removes unused html
* prepares payment amount field to be able to process german inputs like '1.000,50' which is not the international default
* adds modal form for adding payments
* generalizes generic_table_form.html for table-form-like usage in modal_form.html
* adds css enhancements for focused input fields
* adds BaseModalForm as specification to BaseForm, which inherits the BSModalForm class as well
* adds translations
