First version of self-signed certificates support for task subsystem
Add several improvements in certificate manager
Add highlighting restart after successful test connection in YouTrackRepositoryEditor
Add another variant of untrusted certificate dialog
Update untrusted certificate warning dialog: use labels and FormBuilder instead of tables
Update certificate manager to use new dialog
Forget to fill owner's data panel
Update untrusted server's certificate dialog to align labels in all sections equally
Slightly update logic in CertificatesManager and add note about keystore path and password in dialog
[log] Teach RefPainter to draw just some given text, not VcsRef
[log] Group branches in the filter and on the BranchesPanel

Introduce so called expandable groups:
* reference in them are displayed inline.
* in the filter component they are prefixed with a text separator
  indicating the group.
* on branches panel they are expanded and displayed as separate refs.

GitRefManager:
* group local branches into expanded group;
* group tracked remote branches into expanded group;
* group other remote branches into separate groups by the name of
  remote.

BranchesPanel:
* draw expanded groups inline.
* for true-groups draw the name of the group as if it is a reference.
* clicking on the group shows a popup with the list of references.
* clicking on the reference navigates to the commit, in the same way
  as it is done for single-references.

Existing problem: multiple-root branches with same names (both on the
panel and in the filter).
[log] Draw multi-repo flag for ref groups

Assume that all refs in a refgroup belong to a single repository.
This will be changed later.
Merge remote-tracking branch 'origin/master'
Lens improvements