updated doc for BpmHistogram
better naming for rhythm-related extractors, added info and warning for outdated extractors
added TODOs
added missing -lpthread flag for cpptests compilation on Ubuntu
Added option to compile examples as static executables
added header and footer to documentation, new logos
Merge branch 'master' of https://github.com/MTG/essentia
remove PCA over spectral contrast descriptors from extractor

It does not make sense to apply a separate PCA for each analyzed track,
as the basis will be different for each track, thus making impossible to make
comparisons between tehm. We could have applied DCT instead, but opted to
provided raw spectral contrast descriptor.
Fixed overly small width for documentation
Fixed doc generation
Added some doc about logging
added median computation

added median computation to PoolAggregator
new function medianFrames in essentiamath.h
added test for median to the python test
fixed python test testMatrixRealAggregation
Merge branch 'master' of https://github.com/MTG/essentia
changed output of 'bands' to energies instead of log-energies
add option for energy/magnitude output in ERBBands
fixed compilation
compilation fix
added rubatoNumber output to BpmRubato, and updated related algoriths and extractors
Fixed AudioLoader for newer versions of ffmpeg
Fixed broken test audio files