deskutils/docear: Improve port, set maintainership

- Set maintaner to seafork@disroot.org.
- Replace PORTVERSION with DISTVERSION.
- Remove *.exe files and add NO_ARCH.
- Replace png icon from port with one from tarball.
- Replace generated during do-install start script with one in port.
- Use INSTALL_SCRIPT for install start script from tarball instead of
  COPYTREE_SHARE+CHMOD.
- Invoke MKDIR one time for all directories.
- Add TIMESTAMP to distinfo.
- Use %%JDATADIR%% in pkg-plist instead of %%JAVASHAREDIR%%/docear
- Sort pkg-plist.

PR:		288180
Co-authored-by: Amelia Marsh <seafork@disroot.org>