Support abundance matrix source data

[kbraak]

Many species abundance data comes in a form of a matrix with species per row and sites
per column

Original issue reported on code.google.com by wixner on 2014-04-03 10:18:40

[mdoering]

The abundance matrix (called community dataset in R) can be flipped with species as columns. When plots are given as columns one can often find several header rows that provide some event data, e.g. location, aspect, coverage, etc. Example: PonTaurusDIN_A3scr.pdf