Maven->User settings preference page implemented
Predefined button ignores shortcut chars (fixex #573)
Moves WorkbenchShell.closeAllShells() to ShellHanlder.closeNonWorkbenchShells(). Fixes #587
Server requirements runtime is optional. Fixies #616.
Activate FormText in async to avoid UI freeze
Preferences refactoring. Fixes #594.

    - moved WidowPreferencePage to workbench plugin
    - renamed to WorkbenchPreferencePage