Code clean up & housekeeping

[pausz]

This is an umbrella issue to gather:

• code clean ups
• variable renaming acccording to best practices
• intializing variables to specific values
• remove redundancy
• remove circular dependencies

[pausz]

PR #104 improved syntax consistency.

In the original EEGcode the base class QResponse was called firingr which is a more descriptive name of the process represented by that class. Qresponse is tied to the variable name (Q) used to represent a quantity in neural field theory. While the class was renamed, the changes didn't propagate to the configuration files and so firing response is called by writing "Firing: ...". in the configuration files instead of "QResponse: ...".

I propose to rename the base class FiringResponse.

Also, in EEGcode it is clear that plasticity mechanisms, including glutamate dynamics are part of Coupling classes and not Firing responses classes.

Parameters such as theta_a and nu_ab can be modulated (#33) by outgoing postsynaptic activity (Q_a) or incoming activity (phi). Modulation of nu_ab happens via a Coupling class that communicates with a Poulation's firing response or Propagator classes. Modulation of theta_a happens via a Firing derived class like (BurstResponse) or a generalized form of Firing base class that communicates with Propagator classes if theta is modulated by incoming presynaptic activity.