Added Triel Functions~
Merge branch 'IBM' of git://github.com/arnolda/espresso into IBM

Update: Änderung der features.def
Merge branch 'IBM' of git://github.com/Wolfgang-84/Espresso_IBM into wolfgang
Changed name from virtual_sites_trace to lbtracers for formality reasons, trace usually denoting a debug feature.
Change of name Virtual_Sites_Trace -> LBTRACERS
Change virtual_sites_trace -> lbtracers in Makefile.am
Fixed my fix
Correction of the force calculating algorithm in the membrane
Change of sequence in the integration loop to get correct particle-fluid interaction
Cosmetics for easier checks.
Delete remnant forces in halo nodes after the collide/stream step
Added check after position update and appropiate reaction of lbtracers cross box border
Changed triel_tcl input and output, so that blockfiles can be used
small corrections
Minor corrections to the force calculation
small corrections to integration sequence and cleaning of triel code
Update src/triel.h

Correction of algorithm
Added the Neohookean model as a possibility to model the membrane
Merge branch 'IBM' of https://github.com/Wolfgang-84/Espresso_IBM into IBM

Small correction made at hub itself
Merge branch 'IBM' of git://github.com/Wolfgang-84/Espresso_IBM into wolfgang