Unix: add ping6 (closes #821)
Unix: Merge code of ping and ping6.
String: @re: catch “invalid group reference” exceptions. (Fixes second issue of GH-824.)
Misc: Fix typo in l10n-fr.
NickAuth & User: Fix nick auth + gpg auth when secure flag is on. Closes GH-825.
Add support for SASL EXTERNAL
Merge pull request #826 from nyuszika7h/sasl-external

Add support for SASL EXTERNAL
User: Fix @gpg remove with some gpg configs.
src/irclib.py: fix typo causing an error on 904
Later & Seen: Fix neutral grammar in l10n-fr.
Socket: catch connection errors.
Update INSTALL.md

* First note that there is easier installation guide available
* Mention Fedora packages
* Update Debian package links
* Use curl instead of wget as it seems to be more often installed by
default
* Tell to upgrade pip if it fails without doing anything
* Remove duplication of Debian/Fedora package upgrading
* Remove space from pip
Merge pull request #830 from Mkaysi/install

Update INSTALL.md
Fix setting directories when not using advanced mode
Dict: use `*` as default dictionary

The config help is unclear as it talks about `*` meaning all
dictionaries while having default value as empty string.
Anonymous: Fix handling of allowPrivateTarget (after a629f51).
RSS: Make the cache bigger in order to prevent duplicated announces.
RSS: Fix support of feeds that do no have guid fields. Closes GH845.
Owner: Make error message of plugin loading at startup more explicit. Closes GH-850.
PluginDownloader: Sort `repolist` output alphabetically