Bug fixes and improvements for Cutter

[ITAYC0HEN]

Hey, this PR makes the following changes:

• Makes sure to only load PyQt5 when in IDA, Otherwise, use PySide2
• Add context menu actions to select Start and End addresses

• Improve getting hex and disassembly
• Ignore imphash and rich header for non-pe file
• Remove "start/exit" buttons
• Improve UI layout for the checkboxes
• Don't calculate md5 for Cutter because it is already calculated by Cutter

Known issues:
The comments feature doesn't look good as it wasn't designed properly. need a small refactoring in there