Add Wiki details

readme.md - add Wiki link
git_extensions.rst - add Wiki link to Links section, remove link from intro
Merge pull request #33 from rthorp/FIX-Add_Wiki

Add Wiki details
Add logo to RTD and release # to TOC

- added favicon - file gitextensions/bin/logo/git-extensions-logo-final-32.png converted to .ico
- added logo - file gitextensions/bin/logo/git-extensions-logo-final-128.png
- add release number to title on TOC page
Merge pull request #36 from rthorp/fix/Add_logo

Add logo to RTD and release # to TOC
Chapter 2 Updated

Document all settings.
Merge pull request #37 from rthorp/fix/Chapter2

Chapter 2 Updated
In version 2.45 settings are still stored in registry.
Updated version to 2.46
Test Internal Hyperlink Targets