fixed remaining stop flag...
adaptations to nix update, remove command line outputs of units
bugfix for switching off stimulus upon choice2
add sanitizer for section names in nix output
enabled reopening of event_positions and event tags for repeated calls
of repros.

Fixed necessary due to nix updates
solved nix restart issue: all entities are reset upon close()
fix of time resetting issue. resetting of starttime with pushing of next button
Merge branch 'master' of https://github.com/relacs/relacs
add options to switch off side randomization