VERSION v0.10

Fix several bugs.
Typecheck the whole codebase
and drop support for python versions up to 3.4, the latter version included.
Add --sort and --reverse flags to most command line commands, together
with the sort-file configuration option.
see doc.
Add time-stamps in order to sort chronologically documents
see doc.
Add --doc-folder to most command line commands for better bash-scripting
capabilities.
Add --logfile flag in order to dump log messages to a file.
Move papis.utils.format_doc to papis.document.format_doc
in order to minimize circular dependencies.
Add a --profile flag to profile the papis run.
Define a new API for general pickers. (TBD)
Add a citeseerx downloader.

`papis add`

Add --pick, --doc-folder, --all and --sort
flags so that we can choose a document to run the shell or git command
in that folder or in all folders matching a given query introduced by
--pick.