Fix bisection methods to return the parameter that fulfills the conditions more close to the target constrains.

Fix function find_direct_relation. Use a slice based on a chunk size instead of selecting a single time-step.
Check that the constrains are fulfilled after a binary search.

Development

See merge request !15

Merge branch 'development' of gitlab.physik.uni-muenchen.de:w2w/enstools-compression into development

# Conflicts:
#	enstools/compression/cli.py