[log] Don't draw all references on the branches panel: limit by width

Otherwise repaint is slow if there are many refs.
Pass the maximum width to the RefPainter, and don't draw if further
refs would be invisible.

The problem affects only the BranchesPanel: other RefPainter clients
draw a limited amount of refs (only refs on the given commit).
They have other problems though which will be solved later.
unknown variables should not be nullable-enabled after instanceof
IDEA-113698 Getter code generation removing "is" from getter method name
IDEA-113710 Complete Current Statement broken for generic methods
dfa: when merging states by instanceof, don't forget null equivalence
Github: add missing testGitExecutable
Github: fix URL function names
Github: select 'Host' part of url for list of trusted hosts

Before this commit we save 'https://mycompany.com/github' from settings and compare it with 'mycompany.com' from URI
Github: ask if host is trusted on checking credentials

ex: 'Test' buttons, getValidAuth
[log] Optimize ref searching in GraphBuilder.append

* Initially populate a Hash -> VcsRefs multimap and just get values
  while building.
* Pass all VcsRefs to the Branch instead of just the first one,
  so that the Branch could select the one which fits best for it
  needs (for identifying the color - it is any non-tag).