Testsuite release compatible with XRechnung 2.0.1 in version 2020-12-31

This release is compatible with XRechnung 2.0.1.

Added

• src/doc/test-overview.md for further documentation of test cases
• Added construction invoice (04.03a-INVOICE_ubl.xml)

Changed

• Corrected sums (04.01a-INVOICE_ubl.xml)
• Added BT-129, BG-29 und BG-30 to Sub Invoice Lines (04.01a-INVOICE_ubl.xml)
• Added newlines in BT-20 (01.10a-INVOICE_ubl.xml, 01.10a-INVOICE_uncefact.xml)
• Added BT-29 and BT-90 (03.01a-INVOICE_ubl.xml, 03.01a-INVOICE_uncefact.xml)
• Deleted BT-6 where BT-5 is equal (01.01a-INVOICE_.xml - 01.15a-INVOICE_.xml, 03.01a-INVOICE_.xml, 03.02a-INVOICE_.xml)