Added Clipper Library and DocumentSelection class.

*Not fully implemented yet!*
Completed Magic Wand selection modes.

Also added some code to the DocumentSelection class and made the new
"double selection storage" system (consisting of a Cairo.Path and a
List<List<IntPoint>> (no longer using the Clipper to store Polygons))
work all over Pinta (hence the many files that were slightly modified).
Added complete Ellipse Polygon calculations.

Also added more comments in the DocumentSelection class and modified
some History Items a little.
Fixed DocumentSelection.Clone method.

Before, the DocumentSelection.Clone was using "shallow" cloning instead
of "deep" cloning. This was fixed by making the Clone method manually
make a copy of each variable in the DocumentSelection class.
Fixed LassoSelectTool.

When the lassoPolygon was being cleared after the mouse was released
(and after it was added to the doc.Selection.SelectionPolygons
collection), the Polygon inside SelectionPolygons was also being cleared
since it was only referencing to lassoPolygon rather than being a copy.
I fixed this by including System.Linq and then calling the ToList method
on lassoPolygon to make a complete copy of the Polygon.
Added ToolBar for selection modes for the MWT.
Changed MWT selection modes DropDown to ComboBox.

Also updated translations file with new Magic Wand Tool text.
Fixed line width and translation problems.
Optimized calculation of elliptical curves.

The CalculateCurvePoints method was reduced to about 46.46% of the time
(ticks) it took for the old calculation code to execute, on average.
This can be multiplied by 4 for each curve of an ellipse and then by the
number of ellipses that are calculated when the mouse is being dragged.
Overall, it makes the elliptical calculations much faster.
[Fixes bug #987641] Fix reading of TGA files created by Pinta on Linux.

GDK seems to identify TGA files as ICO files if the image ID field is
empty (i.e. the first byte is zero). This change adds some content to
the image ID field so that Pinta can successfully open TGA files that
were created by it.

This is a bit of a hack, but it is allowed by the TGA spec and the
resulting files are still valid TGA files that can be opened by other
applications.
Merge branch 'Magic-Wand-Tool' of https://github.com/mono-soc-2012/Pinta
into mono-soc-2012-Magic-Wand-Tool.

Pull request #31: Magic Wand Tool selection modes.

Conflicts:
	Pinta.Core/Actions/ImageActions.cs
	Pinta.Core/Pinta.Core.csproj
	Pinta.Gui.Widgets/Widgets/Canvas/CanvasRenderer.cs
	Pinta.Tools/Tools/TextTool/TextTool.cs
	Pinta/Actions/Edit/PasteAction.cs
Dispose of the previous selection path if necessary.

This fixes several "programmer is missing a call to Dispose" warnings
that appeared after the Magic Wand selection code was added.
Pulled in the latest translations from Launchpad.
Added the new Georgian translation to the build.
Fix typo in Pinta.Install.proj.
Update the Wix build file.

Added the new Georgian translation.
[Fixes bug #1048137] Fix crash when disposing the ResizeHistoryItem.
Fix several cases where selection paths were not properly disposed.

This issue resulted in several "programmer is missing a call to Dispose"
warnings when redoing or undoing the history items.
[Fixes bug #988278] Improve the error dialog when opening a file fails.

We now show an error message of "Unrecognized image file format" if the
image format is unknown, and an error message of "Permission denied" if
the user tries to open a file that they do not have permissions for.

The styling of the dialog was also changed to make it more consistent
with other dialogs in Pinta.
[Fixes bug #1048502] Fix parenting issues with the Open File error dialog.