Add Diffing Tools using VCDiff

[rapito]

Diffing tools

Adds Diff Tools to allow generating .diff files which only stores relative changes to an original hsd file.

Changes

• Save Diff: saves changes to currently open file in a file with the same name but ending with ".diff"

• Save Diff...: Same as above but you can select the original file and the output diff file name

• Import Diff: Restores the changes stored in a .diff file into the currently open project.

• Tools/Diff Tools: Separate Dialog Window with tools to restore diff changes into a dat file or creating a diff file from the original hsd file and a modified hsd file.

Reason

Allows to share only the changes done to any hsd formatted file.

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The VCDiff.core project was used to as the main diff library and added to the project along with its license.