Merge pull request #175 from Ptizef/master

Some grib_pi improvements
Update translations
Disable chart thumbnails explicitly on entering quilt mode.
Disallow application close if chart database update is in process.
Clarify "SART/PLB(AIS) MOB" message string in Options dialog.
Correct possible fault on cm93 offset dialog after chart switch.
Correct possible fault on route leg info rendering.
Correct a small variety of potential faults, identified by static analysis.
Language template update.
Improve accuracy of ENC LINE feature query select.
Beta 3.3.2302
Add OS X menu items for Preferences and About
OS X menus and menu items

Most of these already work in this commit, but not all.
Some need some more complicated handlers, for which I will make a separate commit for clarity.
Many of the simple ones use the existing handlers for the toolbar buttons, though I have also added several new simple handlers here.

I have extended the SetToolbarItemState function to also set the state of the corresponding menu item, and have used it extensively to replace existing places where the toolbar item state was previously set manually.
OS X menu handlers for mark, route, and measure items

These involved wrapping some of the existing code in chcanv.cpp in function wrappers so I could call it from chart1.cpp.
OS X menu handler for Help menu item

I moved the code to load the external help from about.cpp to chart1.cpp so it is globally available, and I call it from the chart1.cpp menus and also from the original location in about.cpp
Change input com port filter to not put messages on the internal bus if they are filtered out.
Populate route and track segment lengths during load.
Fix disappearing toolbar item bug

Introducing new constants amongst those which define the existing toolbar items triggered a bug in the way toolbar button visibility is calculated.
Fixed by defining new constants AFTER the old ones.
Explanatory comments added.
Add Magnetic COG to the the Dashboard. This has been added to make the output more sensible when using the new Magnetic bearings for route navigation
Add Magnetic COG to the the Dashboard. This has been added to make the output more sensible when using the new Magnetic bearings for route navigation