Improve the syntax

[Nesrinekh]

The syntax right now is not the best, OpenPME code look condensed, no space between lines, the declaration of particles and meshes starting with p and m is not "nice", etc

[lschuetze]

Please correct me, but declarations starting with m and p is nothing to be changed at the syntax level but the simulation code just not need to use those conventions that have been transported over from the C++ code to OpenPME.

In 5062dd8 I already introduced a newline statement into the language. According to the best practices lists should generate such a newline so there is more feeling of a text editor.