Enable calling 'rsshell' without the '.py' extension on Windows

If setup.py is run on Windows and it detects that '.py' is not
included in the PATHEXT environment variable, it will insert a small
additional batch script in ROOT\extbin with the name 'rsshell.cmd'.
This script simply calls extbin\rsshell.py. Since '.cmd' is always in
PATHEXT, rsshell can now be called without needing to type the
extension.
Minor nitpicks in setup.py
Add /wait option to rsshell.cmd
Merge pull request #22 from jgonggrijp/rsshell-ext

Enables Windows users to run `rsshell` without needing to type the .py extension.
Remove redundancy across markdown files
Remove redundancies with wiki from markdown files
Make headers of markdown files uniform
Add mrhmouse to Authors.txt
Revamp Dependencies.md
Revamp Platforms.md
Explain purpose of Authors.txt
Add Tcl/Tk to Dependencies.md
Proper name in Authors.txt
Reorder Readme.md and remove more unnecessary bits
Remove last wiki-redundant bits from Readme.md
Rewrite section 'How' in Readme.md
Add list of available commands to Readme.md under 'What'
Add 'Where' section with pointers to Readme.md
Finishing touches to Readme.md
More finishing touches to Readme.md