Treeportlet: Only try to load the tree if there is a treeportlet.
Merge pull request #255 from 4teamwork/jin-filetree-condition

Treeportlet: Only try to load the tree if there is a treeportlet.
Order imports.
Cleaned up docstrings, fixed typos.
Rename variables to be more meaningful / consistent.
PEP8
Remove redundant component lookup.
Merge pull request #256 from 4teamwork/lg-refactor-document-from-template

Refactor "document from template" view
Updated ftw.zipexport registry entry to multi-value field.
Merge pull request #258 from 4teamwork/lk_update_zipexport_registry

Updated ftw.zipexport registry entry to multi-value field.
Don't pin setuptools&co any more.
Fixed LDAP credentials example in README.
Added new xlsx section.
Moved helper functions to core. PEP8.
Import works.
Set valid_from & valid_to to None if not set.