[log] New icons for expand/collapse branches & show/hide long edges
[log] invokeLater only if needed

It fixes too long collaps of a linear branch.
The performance problem happened because after the branch was collapsed
we jumped to the commit not immediately, but Later,
which happened after JTable repaint.
The repaint on the other hand tried to guess the area to repaint,
but didn't succeed because we were staying in the invalid area,
in which case repaint was called for the whole table
(see BasicTableUI.paint "if (rMin == -1)..."
[log] IDEA-115370 Execute potentially slow tasks under modal progress
[log] Don't allow the graph table to repaint during graph modification

Introduce executeWithoutRepaint() which freezes the repaint while
executing the given task.

Otherwise it may lead to a performance disaster: the graph will
change, and current visible area will be not in the invalid table area,
which will lead to the full table repaint (which in turn will lead to
call getValueAt on all table rows).
[log] Allow null roots in the GraphTableModel.

Some rows may be empty (contain no commits): for instance,
in the case of graph filtered by branch, when there will be just
graph fragments drawn.

Therefore it is not an error to have a null node,
and therefore it is not an error to receive the FAKE_ROOT in the
color manager.

Supply correct root to the LoadingDetails (the root is known because
is taken from the Branch of a Node).
[git] Don't print git log --tags command output to the log & console
[log] toString()
[log] log the error only once per request
 IDEA-115583 exception on CTRL+SHiFT+A on welcome screen
init WEB-6413 sourcemap backed breakpoints do not work until page is loaded
target 1.5 also for testng (IDEA-115618)