shortcut frequently used functions and classes

ParticleAnalyzer, identifyspecies, chooseCode, readDump and readSim are
now directly accessible from postpic (no need to point to the sub
packages).

examples/simpleexample.py

@@ -11,9 +11,9 @@
 
 
 # choose the dummy reader. This reader will create fake data for testing.
-pp.datareader.chooseCode('dummy')
+pp.chooseCode('dummy')
 
-dr = pp.datareader.readDump(3e5)  # Dummyreader takes a float as argument, not a string.
+dr = pp.readDump(3e5)  # Dummyreader takes a float as argument, not a string.
 # set and create directory for pictures.
 savedir = '_examplepictures/'
 import os
@@ -25,7 +25,7 @@
 plotter = pp.plotting.plottercls(dr, outdir=savedir, autosave=True, project='simpleexample')
 
 # we will need a refrence to the ParticleAnalyzer quite often
-from postpic.analyzer import ParticleAnalyzer as PA
+from postpic import ParticleAnalyzer as PA
 
 # create ParticleAnalyzer for every particle species that exists.
 pas = [PA(dr, s) for s in dr.listSpecies()]

postpic/__init__.py

@@ -29,6 +29,13 @@
 
 __all__ = ['datareader', 'analyzer', 'plotting']
 
+# high level functions
+from analyzer import ParticleAnalyzer, identifyspecies
+__all__ += ['ParticleAnalyzer', 'identifyspecies']
+
+from datareader import chooseCode, readDump, readSim
+__all__ += ['chooseCode', 'readDump', 'readSim']
+
 # read version from installed metadata
 from pkg_resources import get_distribution, DistributionNotFound
 try: