Fill README of some plugins. Closes GH-747. Closes GH-749.
schedule: Move the whole deletion of an event in the same critical section.
INSTALL.md: add installing requirements under pip.

It seems that pip ignores `requirements.txt` unless it's installed separately.
INSTALL: install requirements with pip before Limnoria itself.

[SKIP CI]
Merge pull request #753 from Mkaysi/patch-1

INSTALL.md: add installing requirements under pip.
i18n: Don't strip spaces at the end of translated strings. Closes GH-750.
RSS: make more sense to default config

* Change default separator to `|` as used by Topic plugin.
* Show links with manual calling and automatic announcement.
    * In most of cases we want to know where does new RSS feed title point to...
Merge pull request #754 from Mkaysi/patch-1

RSS: make more sense to default config
Delete messages.pot
Revert "Add manual pages for Limnoria* commands as we already have the commands."

This reverts commit d8cd749a861d9956e7aa1162a74f1aa96310e864.
Revert "Merge pull request #657 from Mkaysi/links"

This reverts commit 497df2c14faa5ec00f29f06507cf2b97604f8fd4, reversing
changes made to 21f75b8237a9d61f53e39a0fc643c1a6460e5831.
Merge pull request #758 from Mkaysi/desymlink

Revert #714 & #657 && close #757