Move files into a Maven project structure

While at it, use UTF-8 encoding.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a pom.xml file

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a .gitignore file

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Fix compile failure

This is most likely only papering over a serious issue: since ImageJ
1.47g, the ColorPicker is not a Frame anymore, and hence cannot be
obtained from the WindowManager that way.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>