reword assignment stage update email
disable automatic withdrawal after assignment deadline

fix appraisals count not showing
hide appraisal qualification count
prefer accepting offers of least overloaded fellow
skip deprecated test

fixes #26

fixes #337

complements #336

fixes #336

add assignment deadline extension button for edadmin/authors

fixes #335

fixes #305

fixes #222

fixes #221

fixes #149

method also transfers comment vetting permissions

fixes #185

fixes #198

fixes #125

fixes #118

fixes #268

fixes #213