extend Table class

[azazellochg]

sorted by priority:

• 1) md.iterRows(fn, sortByLabel=XXX) replacement - used in many-many protocols
• 2) md.removeLabel - to remove a column - used in two places to remove magnification and duplicated imageId
• 3) md.copyColumn - used in base to copy angles to priors
• 4) md.SetMdIterator - used when we dont copy all input items to output.

[delarosatrevin]

@azazellochg Do we need this feature of Table class now for Relion 3.1? If not, I would close this issue and open a new one that we can tackle after the plugin release.

[azazellochg]

It is used in polishing output step. It would be good to replace xmipp at some point

[delarosatrevin]

Ok, I will take another look, it didn't seem too complicated to implement.