feat: pdf preview in the print dialog

See merge request !154

Related: #105

fix(Send ERP Mail): uncaught error: call to a member function getMedia() on null

See merge request !153

fix: correctly check if translation of unit exists

See merge request !152

Related: #104

fix: correctly check if translation of unit exists

See merge request !151

(cherry picked from commit 21a31f8f)

Co-authored-by: Patrick Müller <p.mueller@pcsg.de>

Next 3.x

See merge request !150

fix: interface OutputProviderInterface will always evaluate to false

See merge request !148

fix: sepa mandate printing no longer works

See merge request !147

Related: pcsg/buero#476

fix: brutto calc 1 cent problem

See merge request !146

Related: pcsg/buero#425

fix: consider quantity at 1cent fix

See merge request !145

fix: contact person and contact mail are reset

See merge request !144

Related: pcsg/buero#456

fix: when entering gross, note the one cent problem

See merge request !143

Related: pcsg/buero#344
Related: pcsg/buero#436

fix: when entering gross, note the one cent problem

See merge request !142

Related: pcsg/buero#344
Related: pcsg/buero#436

fix: customer id was not passed on correctly

See merge request !141

Customer id was not passed on correctly.
So it happened that the customer id did NOT get into the erp entities.

Related: pcsg/buero#453

fix:  must be of type array, null given

See merge request !139

fix: correct method types

See merge request !138

Next 3.x

See merge request !137