basic particle to particle interaction - coulomb force
added list of charges and masses (only internal), TODO: python
minor fix Q1 * Q2
fixed time level
Merge remote-tracking branch 'l-korous/master' into master-pt
Merge branch 'master' into master-pt
fixes in particle tracing
multiple-particle tracing wrappers (basic implementation)
python wrappers improved
magnetic force introduced (testing needed)
Merge branch 'master' of github.com:hpfem/agros2d into master-pt
Merge branch 'master' of github.com:hpfem/agros2d into master-pt