IDEA-131301 Push dialog has wrong indents in the commit tree view

*expand/collapse tree icons removed for single-repo project
(cherry picked from commit cd15397)
Update link attributes according to baseStyle attributes
(cherry picked from commit 7041a14)
PushDialog: links added to commitNodes, mouseMoved method simplified.
(cherry picked from commit c4debac)
push dialog: commit node renderer improved; tree border added
(cherry picked from commit 7c20ee9)
push dialog: horizontal auto scrolling fixed
(cherry picked from commit 04b8861)
push dialog: do not repaint tree path when loading icon is not visible.
(cherry picked from commit eeb0e9c)
IDEA-130848 Push dialog initial selection & enabling policy

* remember unselected roots and store in workspace.xml;
* don't select and don't load excludedRoots;
* always enable push button for mercurial;
* load all repos for git exclude remembered;
* wait until all or one repo loaded according to sync branch settings;
* always allow push for git new branch;
* preselect git repos only from project view and ignore current editor 'selection'
(cherry picked from commit 2848a16)