Cross-signing with self and user signing keys

Currently translated at 54.3% (224 of 412 strings)

Co-authored-by: Priit Jõerüüt <nhkwlate@joeruut.com>
Translate-URL: https://weblate.nheko.im/projects/nheko/nheko-master/fi/
Translation: Nheko/nheko

This fixes some lag, when Nheko is running, which could affect Nheko and
even other applications by excessively calling fsync. This should be
fine, since all filesystems seem to guarantee order and in most cases,
the modified pages are still written. In the worst case we should only
lose the last /sync results or similar.

lint

Update .gitlab-ci.yml

See merge request !1

Use system icon where applicable

update russian translate

Add GStreamer requirements to README

* add username error label, add word wrapping for error labels

* make lint

* last commits

* remove font, and remove some lambdas

* add QRegularExpression for regex

* improve review things

* add isModified() for checkFields()

* add check isModified() for  all fields in checkFields

* Update src/RegisterPage.cpp

Co-authored-by: DeepBlueV7.X <nicolas.werner@hotmail.de>

* remove emit call for showError

Co-authored-by: DeepBlueV7.X <nicolas.werner@hotmail.de>

Add support for viewing avatar images in full size