Resolve "Do not allow entries in holidays (configurable)"

Closes #112 (closed)

added part::backend part::frontend prio::2 source::customer type::feature labels

added 42 commits

• bebf8a17...ac14107d - 41 commits from branch master
• 1ee57edd - Do not allow entries in holidays (configurable)

Compare with previous version

assigned to @nik

requested review from @ZugBahnHof

marked this merge request as ready

mentioned in commit 053be75f

merged