Add PNGwriter dependency
Require libpng 1.2.9+

... which provides png_set_expand_gray_1_2_4_to_8 that will be required soon
from PNGwriter in https://github.com/ax3l/pngwriter/issues/10
Merge pull request #337 from ax3l/doc-png2gas

Add PNGwriter dependency
Merge pull request #338 from ax3l/topic-libPNGdep

Require libpng 1.2.9+
Fix #267 Valgrind Warnings Uninitialized

Some output in non-live visualization (like png, density)
did depend on uninitialized values.
Cosmetics: Pragma once and Copyright update
Merge pull request #339 from ax3l/fix-pngValgrind

PNG Plugin #267 Valgrind Warnings Uninitialized
First draft

- still not compiling ;)
Fix all compile time errors

- add in Plugin Controller to test compile
Single GPU first running

- (fix) compiles and runs without crash
- (bug) does only find a subset of particles
- (bug) last buffer not flushed -> increase with each notify()
Fix Default Value and first results

- (Fix) Default value now set on 2D and 3D dBuffers
- (Test) SphericMapper written in a more intuitive way
- (Fix) Zone for Particles set to right value in
        calcPhaseSpace() zoneCoreBorder
- (Bug) Still only ending up with 144x1024 instead
        of 128x128x12 particles in phase space
Use Lambda for Assign again

- lambda fixed since eef746a
- still only 144x1024 particles detected
Multi-GPU draft

- needs host::foreach fix (pull comming)
- resets spheric mapper changes (separate pull)
- adds some hints/warnings/todos to FieldEnergy.tpp
- adds 4GPU example
Remove Gather and stay with local result

- Correct SphericMapper: Wrong Rebase result (k3diff)
Add Multi-Phasespace Capability

One can create multiple phase space plots in the same run now.
Add --ps_e Analyser in cfgs

- add PS analyser examples
- remove old files
- fix typo in createParameterSet, choose a word that sounds less horrible
Momentum_Range: transform to desired units
Use new Cell2Particle interface

- PhaseSpace: add charge with CounterShape for now
Documentation and Defines

- public defines for convinience
- more doc
- prepared outsourced output
- SphericMapper: still a wrong line from rebase - corrected
Output draft

- multiple txt files: done (missing units)
- serial splash: draft
- parallel splash: missing