0029009: Configuration - provide a way to get visual dif of SVG images

New helper script svgdiff.bat is added in adm folder.
It can be used for enabling visual diff for SVG images in TortouseGit; see Git guide for details.

dox/dev_guides/git_guide/git_guide.md

@@ -82,7 +82,7 @@ The official repository contains:
 
 @subsection occt_gitguide_1_5 Version of Git
 
-  The repository is tested to work with Git 1.7.6 to 1.7.9. 
+  The repository is tested to work with Git 1.7.6 and above. 
   Please do not use versions below 1.7.1 as they are known to cause troubles.
 
 @section occt_gitguide_2 Installing Tools for Work with Git
@@ -139,6 +139,13 @@ The official repository contains:
   
   @figure{OCCT_GitGuide_V2_image006.png,"",320}
 
+  Optionally, you can set up TortoiseGit to use visual diff utility for SVG images used in OCCT documentation.
+  For that, click on item "Diff Viewer" in the Settings dialog, then click button "Advanced..." on the right tab add new record with the following parameters:
+  - Extension: <code>.svg</code>
+  - External program: <code>&lt;path_to_OCCT&gt;\\adm\\svgdiff.bat %%base %%mine %%bname %%yname</code>
+
+@figure{OCCT_GitGuide_V2_svgdiff.png,"",709}
+
 @subsection occt_gitguide_2_2 Linux platform
 
   We assume that Linux users have Git already installed and available in the *PATH*.