Image comparing tool

[vsmagalhaes]

For validation purposes it is necessary to compare images from different holography runs, and also images produced by different holography software such as AIPS.
This tool will be based on a pre-existing script created by VSM and Currently in use by PPBB.

• Port to astrohack the image comparison tool.
• Adequate User interface to astrohack standards.
• Add possibility to compare multiple images.
• Add a parameter to determine the operations to be done between images.