Begin adding the preview functionality in python2.7, not completed yet.

Samo Penic

2016-07-07 c89a71dbf5ce77d7accc60d8637f0eea64ecc1e6

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Original written by Dan Kroll in FORTRAN. Code was then largely adapted and commented by Miha Fosnaric-Fosni. Rewritten into C by Samo Penic-Peni, with help of Miha's extensive explanations.