add delete particles for GUARD

- add new function to delete particles in GUARD where no neighbor is connected
- delete GUARD particles in TaskParticlesSendelete GUARD particles in TaskParticlesSendd
Avoid mkdir and allocs if disabled
rename deleteParticles()

rename deleteParticles() to deleteGuardParticles()
Merge pull request #364 from ax3l/fix-phaseSpaceDir

Avoid mkdir and allocs if disabled
Merge pull request #363 from psychocoderHPC/topic-freeGuardFrames

delete particle frames in GUARD
defragment memory during shiftParticles

- call fillGaps after every shiftParticles substep
- delete fillGaps call in Particles::update()
delete old comment, update copyright year