Move swapprefix to Picard proper...

... and add similar delprefix
Integrate a couple more plugins ...

eq2 and ne2 by Brian Schweitzer.
Add NEWS.txt item.
Extend eq / ne reather than new eq2 / ne2
Revert reuse of eq/ne and rename again
Adopt simplification proposed by mineo
Fix typo in function documentation.
Use regex, fix typos.
Add tests
Adjust NEWS.txt
Add eq_all, ne_any as requested by Freso
Remove unnecessary for loops (bitmap)
Merge pull request #253 from Sophist-UK/sophist_additional_script_functions

Sophist additional script functions