Merge pull request #1658 from DavidOliver/upload_field_layout

Stopping long filenames in upload field link text breaking page layout. Fixes #1298
Munge .x in the version numbers so the backend is clearer. RE: #1019
Reapply password length migration in 2.3.2 (and retro to 2.3.1). RE: #1648
If a file is missing from the File Upload field, the error will now be shown when the entry is loaded, instead of waiting for a user to save the entry. Fixes #1649
Varied suggested README changes