Bug: a88/f89

Gary Acton reports:
‘Neither the menu selection nor the Ctrl-R or Apple-R
allowed me to use the unanchored PCA.’
A little baffling, since it works for everyone else.
My best guess is that he doesn't realize that ‘Anchor PCA’
is a toggle item which he must disable to get an unanchored PCA,
rather assuming that ‘PCA’ and ‘Anchor PCA’ immediately
calculate anchored and unanchored PCAs respectively.
In this case, it's a problem of poor GUI design and/or poor 
documentation. Probably the easiest fix would be to improve the
documentation, tool tips, and menu item wording.

Note also that GA's next sentence commences
‘I noticed in the PuffinPlot manual that...’
which shows that (if indeed this bug is due to misunderstanding
the GUI) the user did read the manual -- i.e. it's
an ‘unclear documentation’ problem rather than a 
‘user didn't bother reading the documentation’ problem.

Mini-bug which came up while investigating this:
Start Puffin, open new 2G file, open Calcs menu.
‘Use anchoring’ item is unchecked, yet clicking ‘Calculate PCA’
will do an anchored calculation. Workarounds: check and uncheck the
item, or switch to another sample and back again.

Assumed that problems were caused by misunderstanding, and
mitigated them with improved menu item wording, tool-tips,
and documentation.