#1196 Add action menus to panes

[Aaron Madlon-Kay]

OmegaT's panes have some hidden features that are highly undiscoverable, especially on systems with a culture of "principled" usage of context menus (OS X). To address this I have added "Actions & Settings" menus to the toolbars of most panes. Currently they use a "gear" icon.

In addition to items contextually relevant to pane content, these menus also provide access to settings and dialogs relevant to the pane itself (e.g. the Fuzzy Matches action menu offers access to the External TMX Options dialog; the relationship might not otherwise be clear).

[Didier Briel]

Implemented in the released version 4.0 of OmegaT.

Didier