Add plugins extension to MoMA

[julou]

following the skype meeting today, Florian proposed to develop a plugin extension architecture to MoMA (requires ≈2.5 days).
would be useful for e.g.:

• refined length estimation
• refined fluo estimation
• intracellular object tracking

[julou]

thinking again about it, it would be a really useful and probably help keeping a robust core MoMA while every user could ad his layer of custom stuff to fulfil his needs!

do you agree that export in general should be handled by plugins?
the way I see it is that MoMA should be shipped with one default plugin that would implement the current export. This could also be used by other users as a template to write their own plugin…
Hope this remark makes sense.

[julou]

btw this would solve #6