fixes deprecated import
Updates the warning about deprecated. It does not use @decorator
Updates the contribution document.
Minor changes
Minor changes
Fixes documentation issues.
Merge branch 'develop' of localhost:xoutil into develop
Merge remote-tracking branch 'gitlab/fix-deprecated-import' into develop
Merge branch 'develop' of localhost:xoutil into develop
Fix smart_copy object when keys are not strings
Remove duplicated import
Add xoutil.objects.dict_merge function.
Fix a bug in dict_merge.

Not easy to include a test since the bug is buried inside instances_of
and the lack of no_instances.
Promote are_instances and no_instance...

They are now first-class xoutil citizens and have their own
documentation and type check.
Mark next version as 1.5.1.
Fix PEP8 issues
Merge branch 'release-1.5.1'
Remove dev tag
Fix some docstrings.
Fix packaging error in history.