freqtweak THANKS file

FreqTweak has originally been written by Jesse Chappell.

Many people have further contributed to FreqTweak by reporting problems, 
suggesting various improvements, or submitting actual code. Here is
a list of these people. Help me keep it complete and exempt of errors.

- Steve Harris
- Mark Knecht
- Kai Vehmanen
- Takaski Iwai
- Enrique Robledo Arnuncio