Closes #1837.

This fiixes:

error C2797: list initialization inside member initializer list or
non-static data member initializer is not implemented

http://msdn.microsoft.com/en-us/library/dn793970.aspx

Closes #1836.

Rasterized using Inkscape. Fixes the incorrectly blended white fringes
the old icon had at all resolutions below 512x512.

Also includes retina-sized images.

Checks all existing extradata keys and values to ensure that the set
that is being added doesn't already exist.

Closes #1802.

Removes the need for the RTL hacks in BaseGrid as the bugs have been
fixed properly in wx.

Closes #1818.

add '(Language)' after translated labels as suggested on the forums: http://forum.aegisub.org/viewtopic.php?f=5&t=66925#p91569

One spot was missed when converting stuff over to using error_Tag rather
than lua_error for stack unwinding on errors.

This is required for the gc metamethods to actually get run.

It hasn't actually been used for anything for a while, and if a single
normal-priority thread can make your system unresponsive it's time to
upgrade to an OS that's isn't garbage.

Dispatching to the main queue with GCD does not work when there is a
modal dialog active.

Closes #1795.

Targetting 10.7 makes the error handler segfault, and targetting 10.4
appears to work fine.

Closes #1791.