cleanup
another convenient runReadAction
IDEA-101213 Throwable at com.intellij.openapi.options.ex.ConfigurableExtensionPointUtil.buildConfigurablesList
Revert Gregories changes.
decide if the build has work left to be done by scanning all available targets instead only "ModuleBuild" ones
IDEA-100981  added ellipsis at the end of VCS | Mercurial | Merge menu item
Added Icon for  VCS | Mercurial | Merge menu item
Refactor HG action dialogs. Load  hg content (branches) before dialog appears if needed. Execute hg actions as backgroundable tasks.

*Change using structure HgGlobalCommandBuilder to  execute method, which is overridden by inheritors.
*Fixed IDEA-101120,  IDEA-100982 (Mercurial updateTo and merge dialogs are not wide enough by default) - now we load branches for all hg repositories before dialog constructor called.
*Fixed IDEA-100985 Mercurial Merge was executed in AWT thread, now we call it in backgroundable task. (and other actions too).
*Store all branches for all repositories in Merge and Switch (UpdateTo)dialog.
IDEA-100984 - a title for Mercurial Merge dialog added.
IDEA-100983 Mercurial merge dialog should save its dimensions
IDEA-101121 Mercurial UpdateTo dialog should save its dimensions
Move saveAllDocuments method to AWT (because it produce a error).
Rename HgSwitchWorkingDirectoryAction and HgSwitchDialog to HgUpdateToAction and HgUpdateToDialog. Change appropriate action text and description.
EA-41258 check validity of range marker
EA-37280 avoid surprise NPE: check if specific GotoDeclarationHandler returned null element in array
Windows launcher: splash