close on autosave and minor bug fix.
added sphinx documentation tree.

doc is more a skel than usable yet...
bugfixed particleanalyzer, in case it has no particles.
Merge branch 'master' of github.com:skuschel/postpic
added very simple getting started doc page+script.
reuse already created data in histogram functions.

This gives a speedup when working with large particle numbers. For example
a 72e6 particle processing got speed up from 65sec to 52sec.
Merge branch 'master' of github.com:skuschel/postpic
less memory consumption of _SingleSpeciesAnalyzer internals.

The _SingleSpeciesAnalyzer is now requesting the data on demand of the
application. This is particularly useful if working with a huge number
of particles and only requesting some of their properties. This leads to
significantly less memory consumption. See benchmark results below.

Additionally data will be cached inside the _SingleSpeciesAnalyzer if
and only if the 'compress' function was used. Since sorting of particles
by conditions takes time (particles.py: line 60), this leads to a speed
up of the data processing (compared to no caching).

Benchmark with 72e6 particles creating 4 figures making heavy use of
compression functions.
Measured with '/usr/bin/time -v':
                      wall time , max resident set size
before this commit:      11.7sec, 6.78GB
no caching:              17.9sec, 2.44GB
only compressed caching: 11.3sec, 2.74GB  <= selected now.
always caching:          10.9sec, 3.40GB
Do not copy data in memory when counting particles

counting the number of particles of a ParticleAnalyzer created a full
list of particles and was then just returning its length. Assembling the
this list of particles always copied them in memory. The number of
particles is now counted without this additional data copying.
make the visitreader to work with any dumpreader

The Visitreader stores the information about the dumpreader class that
should be used to read the dumps. This will allow to read full
Simulations via visitfiles written by different codes simultaneously.
mocking dependencies for readthedocs.org
added readthedocs badge
Update CONTRIBUTING.md
new files: epochhdf5.py + h5example.py

created epochhdf5 reader. not tried yet.
created h5example.py not tried yet
changed in datareader __init__.py
postpic.datareader.chooseCode()   added:

elif code in ['hdf5', 'HDF5', 'h5']:
from epochhdf5 import H5reader, Visitreader
setdumpreadercls(H5reader)
setsimreadercls(Visitreader)
minor changes

now code is at least semantically right
new implementation of vsimhdf5.py

tested if methods return right value (except getderived all methods
implemented). Using _const.axesidentify for x,y,z,px,py,pz; weight and
ID not included. All other methods should behave like for sdf.
Neverthelerss additional esting required--
reviewed, shortened

self.time() somehow doesn't work. But self.time does! reviewed and
deleted some outdated comments.
implemented Stephans change comments
merged