Add several useful features to draw rectangle

[troyane]

Hi! I'm actively using this app, and found that features I've implemented can be really useful for you:

• Ability to easily find drawn rectangle -- using vertical and horizontal lines around it
• Ability to insert rectangle coords from tesseract output
• Ignoring rectangle (0, 0, 0, 0)

Also, I think its better to name it correctly: Qt Box Editor, but do not use acronym QT -- as it is written here:

Qt is a cross-platform application development framework, but QT (QuickTime) - is an extensible multimedia framework developed by Apple Inc.

[zdenop]

thanks

[troyane]

Cool. I'm going to work on this app further. It helps me lot and I'm going to help it too :) Also there are several bugs I faced. Probably, I'll open issues for it.