Added more missing init functions
Extracted NEST meta code to external module.
Extracted adaptation logic into new object.

...called `BoundedAdaptationRunner`.
Added flags in meta fns. to block exc. or inh.

Internally, the corresponding connections will just not be created (total blocking).
Bugfix: Typo in variable name.
Network builder can now be limited to subnetwork.

These subnetworks (right now) have to be declared already in the YAML topology file, and the neurons of a given subnetwork have to be grouped in YAML.
Burst detection threshold is now a fn. argument

Used to be a fixed constant.
YAML exporter can handle arbitrary additional info
More sensitive burst detection parameters.

To avoid detecting localized events as full bursts.
Added a script to add inhibition to purely excitatory networks
Merge commit '7c79269cbdfbe50a4ea665dbd501f6ae80236ec1'