Bug 36193: (follow-up) Use buttons and don't nest forms

Bug 36193: (follow-up) Use buttons and don't nest forms

When changing action links into forms, we should use a submit button rather than JS to submit

Receipt cancelling needed a form embedded in the page as we cannot nest forms

Fixed searching on invoice.pl

Fixed resetting mappings (original button did not need cud-)

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>